Diseases of the skin

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Preface To The Second Edition

The rapid exhaustion of the first edition within less than eighteen months after its appearance has made necessary a new one. In the preparation of this new edition the text has been carefully gone over, a number of minor errors corrected and some new material added containing largely matter omitted through inadvertence in the first edition. The most important change is the addition of an entire new section in which are discussed some affections of the mucous membranes continuous with or adjacent to the skin which occur either in connection with certain cutaneous affections, or as independent diseases which frequently come under the observation and care of the dermatologist. Among the latter are discussed leucoplakia, a most important affection, to the symptoms and etiology of which considerable space is devoted, exfoliatio areata linguae (the so-called geographical tongue), black or hairy tongue, Moller's glossitis, median glossitis, a variety of inflammation of the tongue quite recently described for the first time by the French, cheilitis glandularis, cheilitis exfoliativa, perleche, aphthous stomatitis and Fordyce's disease. A number of new illustrations, both clinical and histological, have been introduced, and the index has undergone a most thorough revision and considerable amplification, for which the author is indebted to his onetime assistant, Dr. Samuel Horton Brown, to whom he here expresses his thanks.

In conclusion, a few words may be said about the classification which, perhaps, ought to have been said in the preface to the first edition. In order to make the classification a uniform one based only upon pathology and histopathology, the class of Parasitic Diseases based upon etiology has been abandoned and the members of the group, with one exception, transferred to the Inflammations where they may very properly be placed. Under this arrangement, however, tinea versicolor, not being in any sense an inflammatory affection, had to be separated from the other members of the group and another place found for it ; on account of its most prominent and characteristic symptom it has been placed for the present among the Anomalies of Pigmentation.

M. B. Hartzell.

Philadelphia, April, 1919.

Preface

This treatise, which is based very largely upon the author's own experience as a worker and teacher in this special department of Medicine for more than twenty-five years, has been prepared as a text-book for the student of Medicine, as a practical guide for the general practitioner in the recognition and treatment of diseases of the skin and as a work of reference for the dermatologist.

In the preparation of the work the author has not only drawm upon his own experience, but, in order to present the views held by the most eminent authorities, he has made liberal use of the standard treatises of other authors, both American and European, and he desires here especially to acknowledge his indebtedness to those two monuments of industry and learning, La Pratique Dermatologique and Mracek's Handbuch der Hautkrankheiten.

While the author has endeavored to fully present the views held by his co-workers in this very active field of medical research, he has not hesitated to express his own when they differed from those generally accepted ; and when he has thus differed it was because he believed his experience justified it.

A not inconsiderable experience in general medicine extending over some years has especially enabled the author, as he believes, to survey the subject from the view-point of the general practitioner as well as from that of the specialist, and, keeping the special needs of the former prominently in mind, he has endeavored to describe the numerous varied and ever-varying symptoms of cutaneous disease lucidly and concisely, avoiding overelaboration and at the same time omitting nothing of real importance.

Considerable space has been given to the subjects of etiology and pathology, since a knowledge of these must lie at the foundation of all rational treatment and prophylaxis ; indeed, without such knowledge treatment is a mere blind groping in the dark and prophylaxis a vain delusion.

In the sections devoted to treatment every effort has been made to include all the remedies and methods of treatment of approved value and especially those which the author's own experience has led him to rely upon. The manner of using local remedies has been gone into at considerable length, since success or failure depends quite as much upon the manner of their employment as their selection ; indeed, an indifferent remedy used with intelligence is frequently more efficacious than the best used without attention to apparently unimportant details.

Recognizing the great aid to be derived from well-made illustrations, liberal use has been made of the author's own large collection of photographs, a considerable number of them color photographs, which represent

VI 11

PREFACE cutaneous eruptions with an accuracy and fidelity to nature quite unattainable in any other form of illustration. A very considerable number of photomicrographs have been introduced which the author hopes will aid materially in the elucidation of the text devoted to pathology.

In conclusion the author desires to express his great appreciation of the liberality and unvarying courtesy of the publishers, the J. B. Lippincott Company.

M. B. H.

Philadelphia, October, 1917.

Contents

Chapter Page

I. Anatomy i

II. General Symptomatology 17

Chapter I

The skin is an elastic membrane of variable thickness covering the entire body. It varies in color from the pinkish-white of the European through various shades of brown to the black of the African, the variations in color depending chiefly upon the amount of brown pigment present. Even in the white races there is considerable pigmentation, which is more marked in particular localities, such as the axillae, the areola of the nipple, the external genitalia, and the eyelids. It is not perfectly smooth, but is marked by numerous furrows and ridges which divide its surface into small lozenge-shaped areas, or, upon the palms and soles, produce peculiar patterns, each individual having his own special pattern. About the joints where the skin is subject to extensive movement these are much more marked than in other situations. It is to be regarded not simply as a protective membrane, but as an organ of great complexity, abundantly provided with blood-vessels, lymphatics, nerves, having certain appendages, such as the sweat- and sebaceous glands, the hair and nails, and having certain functions the proper performance of which is more or less necessary, not only to the maintenance of the health of the skin itself, but to the health of the individual. It is divided into three parts, which are, beginning with the surface, the epidermis, the corium, and the subcutaneous connective-tissue ; the two former, while closely united, are yet quite distinct the one from the other in structure and origin, the epidermis being derived from the ectoderm, while the corium is of mesoblastic origin (Fig. i).

The epidermis is composed of four layers of epithelial cells, more or less distinct, which are, proceeding from without inwards, the corneous layer or stratum corneum, the clear layer or stratum lucidum, the granular layer or stratum granulosum, and the stratum germinativum, also known as the rete mucosum, the rete Malpighii, or the prickle-cell layer. This last layer is the actively growing part of the epidermis and is the most important portion of it.

The stratum corneum or horny layer (see Fig. i, s. c.) is of variable thickness. In certain regions, such as the palms and soles, it is very much thicker than upon the trunk. According to locality, it is composed of a few or many layers of flat, in section quite elongate, translucent cells, of horny material from which the nuclei have disappeared, although here and there remains of a nucleus may be perceived in some of the cells of the lowest layer. The cells of this layer are being constantly exfoliated and as constantly renewed from below. Its function is chiefly, if not exclusively, a protective one, protecting the soft mucous layer which lies beneath it.

Immediately beneath the stratum corneum are two or three rows of flat, clear cells — the stratum lucidum — which in sections of the skin appear as a narrow, bright band separating the stratum corneum above from the stratum granulosum below. This layer is practically a part of the corneous layer.

Fig. i. — Section of the epidermis and upper portion of the corium. s. c, stratum corneum, horny layer; 5. /., stratum lucidum, clear layer; s. g., stratum granulosum, granular layer; r. m., rete mucosum; c, corium; s.d., upper portion of sweat-duct.

The granular layer, which in stained sections (see Fig. i) of the skin is one of the most conspicuous layers of the epidermis, consists of two or three rows of cells which in section are elongate ovals, lying horizontally, containing rather ill-defined, imperfectly staining nuclei, in the protoplasm of which are numerous granules. The nature of these granules is still a matter of some debate. It is supposed by some investigators that there are two substances — eleidin, which exists as droplets of fluid in the cell, and keratohyalin, a solid substance exhibiting the reaction of hyaline material. It seems most likely that there is a single substance, keratohyalin, which is fluid or solid according to the age of the cell, and that the appearance of this material in the cell is a part of the process of cornification.

The stratum germinativum, or, as it is more commonly called, the rete mucosum (Fig. i), is the thickest of the layers of the epidermis and is composed of oval, polygonal, and columnar cells with large round nuclei, the oval cells being situated in the upper part, the polygonal in the middle and lower portions, while the columnar cells form a single row, the basal-cell layer, standing more or less at right angles to the undulatory line separating the epidermis from the papillary layer of the corium. The cells of this portion of the epidermis are connected with one another by slender protoplasmic

Fig. 2. — Cells of the rete mucosum, the so-called "prickle-cells." Note fine intercellular filaments.

bridges (Fig. 2) which give them, when seen in profile, the appearance of being covered with small spines like a burr, and for this reason they are sometimes spoken of as prickle-cells. The cells of this layer contain numerous fine fibres running in various directions in those centrally situated, but in the columnar cells they pursue a course parallel with the long axis of the cell. These fibres, which were designated protoplasmic fibres by Kromayer, are supposed by Weidenreich to form the intercellular bridges which connect the cells of this layer. Between the cells of the basal layer, starting at the junction of the epidermis with the corium, are numerous fine spiral fibrils. These fibres, which require special methods of staining to demonstrate them, were first described by Herxheimer and are consequently known as Herxheimer's spirals. Although most abundant in the lowest parts of the epidermis, they may, under certain pathological conditions, extend up to and within the horny layer, according to Eddowes. The nature of these spirals is somewhat uncertain ; Herxheimer thought they represented juice channels; Eddowes regards them as fibrin, while Kromayer thinks he has demonstrated their protoplasmic nature.

The corium (Fig. i, c.)) derma, or true skin, as it is sometimes called, lies immediately below and in contact with the epidermis, sharply separated from it by an undulatory line. It is composed of coarse bundles of interlacing fibrous tissue, collagen, surrounded by finer elastic fibres composed of elastin, and a moderate number of connective-tissue cells, most abundant in the neighborhood of the larger vessels. It contains blood-vessels in abundance, nerves, lymphatics, hair follicles, sebaceous glands, and muscles. It is divided into two parts — the pars papillaris, the portion immediately underlying the epidermis, and the pars reticularis, the deeper portion — these two not being separated by any sharp line of division, but passing insensibly into each other. The pars papillaris is made up of numerous small nipple-like elevations which fit into corresponding depressions on the under surface of the rete mucosum. Most of these papillae are provided with blood-vessels running parallel with their long axis and terminating in capillary loops. A lesser number also contain nerve-endings in the shape of tactile corpuscles. The number, size, and arrangement of these papillae vary greatly according to location. Upon the palms and soles they are arranged in curving lines, while upon the finger-tips they form oval patterns of concentric lines which, owing to the fact that no two individuals have precisely the same pattern, are employed under certain conditions for purposes of identification.

In the pars reticularis the bundles of fibrous tissue are coarser than in the papillary portion and form a looser mesh-work. Immediately beneath the pars reticularis, and practically forming a part of it, is the subcutaneous connective-tissue or stratum subcutaneum. In this portion of the derma the meshes formed by the fibrous tissue are large and usually contain a considerable number of fat-lobules. The sweat- or coil-glands, some of the hair papillae, and the Pacinian corpuscles are found in this portion of the derma.

In those regions where the fat is abundant it forms the panniculus adiposus.

The skin contains a brown pigment, melanin, which in the white races is much more abundant in some regions than in others, such as the genitalia of both sexes and the areola of the nipple in women. It occurs as yellowish or brown granules, which in white-skinned individuals are found almost exclusively in the lowest layer of cells of the rete, but in the negro are present in all parts of the rete up to the stratum corneum. Scattered pigmented cells are also present in the upper portion of the corium.

Blood-vessels. — The skin contains numerous blood-vessels which form two horizontal plexuses, a superficial and a deep one. The former, lying just beneath the papillary layer of the corium, sends minute capillary loops to the papillae, while the latter, composed of much larger vessels and lying much deeper in the subcutaneous tissue, supplies the sebaceous and sweat-glands and the hair papillae. The epidermis is without blood-vessels.

The lymphatic circulation of the skin consists of an extensive arrangement of channels without special walls, the so-called juice spaces of Unna, and lymphatic vessels lined with endothelium. The juice spaces are found between the cells of the rete mucosum, in the papillae, about the excretory ducts of the sweat-glands, the sebaceous glands, hair follicles, about the fibres of the corium, and the muscles. The lymphatic vessels form plexuses corresponding in a general way with the blood-vessel plexuses. The lymph flows from the apices of the papillae into the epidermis and returns by way of the interpapillary prolongations of the rete.

Nerves. — The skin contains many nerves both of the medullated and non-medullated varieties. The trunks which supply the skin accompany, for the most part, the larger vessels situated in the subcutaneous tissue, and give off branches which ascend through the corium, supplying in their course upwards the various glands, muscles, and hair papillae found in this structure, and forming a fine network of nerve-fibres immediately beneath the epidermis, from w r hich fine fibrils penetrate the rete. The medullated nerve-fibres end in certain peculiar corpuscles, of which there are three principal varieties — the corpuscles of Krause, the corpuscles of Meissner, and the Pacinian corpuscles or corpuscles of Vater.

The corpuscles of Krause (Kolbenkorperchen) are globular or ovoid bodies surrounded by a connective-tissue capsule having two or three layers composed of flat cells and containing an inner bulb penetrated by a nerve fibril or fibrils which have lost their medulla. These bodies are found on the glans penis, the clitoris, the inner surface of the prepuce, the mucous membrane of the lips, the tongue, and conjunctiva of the lids.

The corpuscles of Meissner and Wagner, tactile corpuscles (Fig. 3) (Tastkorperchen), are oval bodies surrounded by a thin, occasionally laminated capsule, the surface of which is transversely striated. These bodies receive medullated nerves, which on entering the corpuscle lose their medulla and divide up into numerous fine branches which present irregular or spindle-shaped thickenings or swellings, and which form an irregular network within the corpuscle. They are found in the papillae of the corium, most abundantly on the palms of the hands and soles of the feet, each papilla containing usually one, but sometimes several, corpuscles.

The Pacinian corpuscles, or corpuscles of Vater, are the largest of the corpuscular nerve-endings, being visible to the naked eye. They are ovoid or pear-shaped bodies, found most abundantly in the skin of the finger-tips, but are present also upon the palms and soles, the backs of the hands and feet, upon the upper extremities, the nipples, and the genitalia. They are situated in the deepest part of the reticular portion of the corium and in the subcutaneous connective tissue. Like the other nerve corpuscles, they are surrounded by a laminated capsule composed of many concentric layers of connective tissue, within which is a central core containing the terminal

nerve-fibre, which loses its medulla on passing from the capsule into the core.

The terminal nerve-fibre passes through the centre of the corpuscle, in the direction of its long axis, terminating at the distal pole in a club-shaped thickening, or, what is less frequent, dividing up into two or three small branches with slightly thickened ends.

Each corpuscle is supplied with blood by two or three small vessels which enter it usually at the poles and divide into a fine vascular network under the external layer of the capsule.

Still another form of nerve endorgan, situated in the lowest portion of the corium and in the subcutaneous tissue, has been recently described by Ruffini. These are spindle-shaped bodies composed of connective tissue and elastic fibres running in the direction of their long axis.

Each of the corpuscles is provided with a single nerve branch which enters at the side, or, less frequently, at the end, and divides up within the connective tissue to form an anastomosing network of fine fibres upon which are numerous swellings (Rabl, Mracek's Handbook). The blood supply is obtained from a rich capillary network which covers the surface but does not penetrate the interior of the organ.

As "touch-cells," Merkel has described certain oval nucleated cells found in small numbers only in the epidermis and upper portion of the corium ; these he regards as nerve-cells which are connected with nerve-fibres. Krause, however, does not consider them as in any way connected with the nerves, but as epidermis cells which have undergone mitosis. They are found in those localities where tactile corpuscles are few, as the skin of the abdomen, although Kolliker found them upon the finger-tips and upon the soles. The real nature of these cells is still a subject of debate.

Fig.

-Tactile corpuscle.

Muscle. — Both striped and unstriped muscles are present in the skin. The former are found chiefly in the face and neck as scanty fibres which, taking their origin from more deeply-seated muscles, are distributed to the lips, nose, eyebrows, and chin. These are analogous to the muscles which exist in certain of the lower animals by which extensive movements of the skin may be produced.

The unstriped or smooth muscles exist as fasciculi associated with the hair and glands or as membranous expansions in the scrotum, forming the tunica dartos, in the areola of the breast, and in the nipple, the last arranged as circular bundles. The unstriped muscles connected w r ith the hair follicles, named arrectores pilorum, usually arise by several small fasciculi from the papillary layer of the corium, and are inserted in the side of the hair follicles, which they join at an acute angle about the level of the hair papilla, including in the angle thus formed a sebaceous gland. Within and around these muscles are numerous elastic fibres by which they are connected with the fibrous bundles of the corium and subcutaneous connective tissue. Contraction of the arrectores pilorum causes that peculiar condition of the skin known as cutis anserina, or "goose skin," and the erection of the hair such as is seen in some of the lower animals when enraged. Owing to their situation in the angle between the muscle and the hair follicle, the sebaceous glands are compressed by the arrectores, which thus serve as expulsors of the sebum ; and they also serve by their contraction and relaxation to regulate the amount of blood in the vessels of the corium.

Pigment. — The color of the skin, while due in some part to other causes, depends chiefly upon the presence of a yellowish-brown granular pigment, melanin, contained in the cells of the epidermis, especially in those of the lowest layers of the rete, although in the dark races and in certain pathological conditions pigment-bearing cells are found in the upper part of the corium as well. In the white races the pigmentation of the skin is not uniform, but varies considerably in different parts of the body, being most marked in the axillae, in the nipple and its areola, the external genitalia, and about the anus. According to most authors, pigment granules are never present in the cells of the horny layer of the epidermis, even in" the dark races, there being only a slight diffuse discoloration of these ; but Rabl found them in the corneous cells of the nipple of a nursing woman. In fair skins it is found almost exclusively in the basal cells of the rete mucosum deposited about the nucleus, but in dark skins several rows of cells contain pigment scattered throughout the body of the cell, this pigmentary deposit showing as a dark-brown undulatory line following the contour of the papillary layer of the corium. The origin of melanin is still a matter of debate. Some investigators (Aeby, Riehl, Ehrmann) maintain that it is carried from the corium and subcutaneous tissues to the cells of the epidermis by certain pigment-containing cells, chromatophores, w r hile others (Jarisch, Schwalbe) believe that the pigment is formed in the epidermal cells themselves.

8 DISEASES OF THE SKIM,

The experiments of Karg, while not conclusive, would seem to favor the former view. This investigator, who transplanted white skin into the skin of the negro, found large branched cells at the boundary line between the corium and the epidermis, which, sending long processes upward into the spaces between the epidermal cells, transferred pigment to them so that at the end of six weeks the transformation of the white into black skin was complete. The function of this pigment is without doubt to protect the skin from the injurious effects of the actinic rays of light, and it is greatly increased in quantity in parts exposed for any length of time to the rays of the sun, of the electric arc light, and to the X-rays.

Hair is present upon all parts of the skin except the palms and soles, the dorsal surface of the terminal phalanges of the fingers and toes, and the penis. There are three quite distinct varieties: long, soft hair, such as is found upon the scalp, in the axilla, and upon the pubes ; short, stiff hair found in the eyebrows, eyelashes (cilia), in the nostrils (vibrissas), and in the external auditory meatus; and soft, fine, for the most part unpigmented, hair or down designated lanugo, present upon the face outside of the bearded region, the trunk, and extremities.

The hair is contained in tube-like depressions extending deeply into the corium and subcutaneous tissues, lined with epithelium, known as hair follicles, each follicle containing, as a rule, one hair, but not infrequently two, three, or more. The portion which projects beyond the mouth of the follicle is known as the shaft, while that within the follicle is called the root, terminating in a swollen extremity, the hair bulb, which surrounds the hair papilla at the bottom of the follicle. It is composed of three parts — the cortex, the cuticle, and the medulla, this last being absent in the lanugo hair and in the free extremity of the long hair. The cortex, which forms the principal part of the hair, is composed of slender bundles of long spindle-shaped horny cells, usually without nuclei, whose long axis corresponds with that of the hair, frequently containing granules of dark pigment.

In the lower portion of the root the cells of the cortex are less elongate, contain nuclei, and are softer, owing to less complete cornification, and, as one approaches the bulb, the cells become oval or polygonal, resembling those of the rete mucosum of the epidermis.

The cuticle of the hair (cuticula pili) , which covers it, consists of thin, translucent, irregular quadrilateral cells without nuclei, which overlap one another like tiles on a roof, their free borders projecting at a slight angle and directed toward the end of the hair.

A medulla is present, as a rule, only in the thicker hairs, being absent in the foetal and lanugo hairs, and it is occasionally absent even in the hair of the scalp. It consists of clear, nucleated cubical cells contained in a central canal, and extends from the bulb to within a short distance of the free end, where it disappears. These cells contain a few granules of keratohyalin and of pigment and numerous air vesicles which give to the marrow, black by transmitted light, a lustrous white appearance when viewed by reflected light. In the upper portion of the hair the cells of the medulla undergo atrophy, the nuclei disappear, and air vesicles appear between the cells as well as within them.

The hair follicle ( Fig. 4) , in which the hair is contained, may be regarded as an invagination of the epidermis into the corium. It is a narrow tube composed of connective tissue lined with epithelium, with a funnel-shaped mouth, slightly constricted some distance below the external opening at the point where the sebaceous-gland duct opens into it, with a bulbous expansion at the bottom into which projects the hair papilla. The connective-tissue portion of the follicle is derived from the corium and consists of two layers — an external layer in which the fibres run parallel with the long axis of the follicle, and an internal one in which the fibres are arranged circularly around it and contain numerous rod-shaped nuclei. In the lower half of the follicle the inner fibrous layer is separated from the epithelial lining by a thin, transparent membrane, the vitreous membrane, w r hich increases in thickness as the bottom of the follicle is approached, then becomes thinner until it disappears completely at the base of the papilla. The internal surface of this membrane, or the one turned toward the epithelial lining of the follicle, presents numerous transverse ridges or furrows which fit into corresponding depressions and elevations in the basal layer of the epithelial cells.

The epithelial lining of the follicle is continuous with the epidermis, and down to the neck of the follicle, the point where the sebaceous glands open into it, is identical in structure with it, but at this point the stratum corneum and the stratum granulosum disappear. It is divided into two layers or sheaths, the external root-sheath and the internal root-sheath. The external root-sheath is a continuation of the rete Malpighii of the epidermis and is composed of nucleated polygonal cells resembling the cells of that portion of the epidermis. Its thickness diminishes as the bottom of the follicle is approached until, at the base of the papilla, it may contain but a single row of cells. Unna has proposed to call this the "prickle-cell layer of the hair follicle" instead of external root-sheath.

The inner root-sheath, closely connected with the external sheath, extends from the neck of the follicle to the neck of the hair papilla, and is composed of three layers of cells more or less distinct — an outside layer, the layer of Henle, consisting of a single row of polygonal nucleated cells ; a middle layer, the layer of Huxley, in which the cells are also polygonal and contain granules of keratohyalin ; and an inner layer, the cuticle of the follicle, consisting of elongate cells which have their long axes transverse to the axis of the follicle, and which, as they approach the follicular neck, become more or less oblique and interlock w T ith the cells of the cuticle of the hair shaft. The cells which compose the several layers of the inner root-sheath undergo cornification as they near the mouth of the follicle, become more elongate, and lose their nuclei.

The papilla which occupies the bottom of the follicle is a pear-shaped projection composed of connective-tissue fibres from which the hair is produced, the medulla growing from the top, while the cortex of the shaft is produced by the sides. According to Rabl, hairs which show a strongly growing medulla are seated upon papillae which have pointed tops, while the lanugo and hair in which the growth of the medulla has come to a standstill are found on papillae with rounded tops.

The follicles may occur singly or in small groups, the latter being the usual arrangement upon the scalp. They are never placed at right angles to the skin, but more or less obliquely, extending to a depth varying from 2 to 7 mm., in the case of the strong hairs, down into the subcutaneous tissue, while the lanugo hair does not reach below the corium.

Sebaceous Glands. — All hair follicles, practically without exception, are provided with glands, known as sebaceous glands, which secrete a fatty substance, the sebum, which is discharged into the follicle, or, in some instances, directly upon the skin, and serves to lubricate the hair and the skin. The number occurring within each follicle varies from two to six or eight (Fig. 4).

They occur in several forms, the simplest being a rather short pyriform tube lined with epithelium, while those connected with the follicles of well-developed hairs, such as the hairs of the scalp, are racemose glands with a variable number of lobules, and a duct through which the sebum is discharged into the follicle some distance below its mouth. In the case of the lanugo hairs, the gland is often quite as large and well developed as the follicle, the hair occupying the excretory duct of the gland which opens directly upon the surface. They are provided with a connective-tissue covering derived from the corium, which is lined with a thin membrane, the membrana propria. The lobules have no lumen, but are filled with epithelial cells, the most external layer of which, cubical in shape, with a round or oval nucleus and granular contents, are seated upon the membrana propria. Those occupying the more central part of the lobule are polygonal in shape and contain a clear protoplasm in which are minute drops of fat, the amount of fat increasing as the centre of the lobules is approached. Among the largest and most complex of these glands are those found upon the nose ; they are frequently quite large and contain many lobules. The ducts are lined with several layers of epithelium which are continuous with the rete mucosum lining the mouth of the follicle.