Follicular Mucinosis

The basis of follicular mucinosis is degenerative changes in the hair follicle and sebaceous glands with the destruction of their structure and the deposition of glucosaminoglycans (mucin). Reticular erythematous mucinosis (syn: REM-syndrome) was first described by L. Lischka and D. Ortheberger (1972), followed by K. Steigleder et al. (1974).

[1], [2]

Causes of the follicular mucinosis

The causes and pathogenesis of follicular mucinosis have not been fully established to date. The causes of violations of chemistry and the structure of the basic substance of connective tissue are unclear. 

[3], [4]

Risk factors

Starting factors may be viral, bacterial infections, disorders of the endocrine, immune systems, pathology of internal organs.

Under the influence of causative factors there is a local violation of the synthesis of fibroblasts of the main substance of connective tissue and collagen with the formation of mucin.

[5], [6], [7], [8], [9], [10], [11]

Pathogenesis

At the heart of the disease is a special kind of necrobiotic changes in the epithelium of the hair follicles, caused by the appearance in it of a mucinous substance. The cause of the disease is unknown. N. Wolff et al. (1978) consider follicular mucinosis as a type of histological reaction common to a wide variety of unrelated stimuli and is a reflection of violations of intraepithelial metabolism. According to EJ Grussendof-Conen et al. (1984), a significant pathogenetic factor is a violation of the processes of differentiation of the sebaceous glands.

Histopathology

Degenerative changes in hair follicles and sebaceous glands are observed with the formation of cystic cavities filled with homogeneous masses (mucins) rich in glycosaminoglycans. Sometimes mucin is not found. In the dermis there is an infiltrate consisting of lymphocytes and histiocytes, sometimes with the presence of eosinophils, obese and giant cells.

Degenerative changes in follicles with these forms are similar, the difference is that with the symptomatic variant other characteristic histological signs of the underlying disease also appear. In addition, with symptomatic (secondary) mucinosis associated with fungal mycosis, the inflammatory infiltrate consists of cells peculiar to the fungal mycosis with microabscesses of the Sacrifica in the epidermis.

[12], [13], [14], [15], [16], [17], [18], [19]

Pathomorphology

The epidermis is unchanged, only the lengthening of the epidermal processes, hyperkeratosis and focal spongiosis in the basal layer are sometimes observed. In the upper third of the dermis, less often in its deep sections, there are perivascular and perifollicular infiltrates of a lymphocyte character with an admixture of macrophages and individual tissue basophils. Vessel enlargement and swelling of the upper dermis are noted, where glycosaminoglycans such as hyaluronic acid are found. Characteristic for REM-syndrome, the perivascular lymphocytic infiltrate and congestions of the mucus-like substance between collagen fibers give it similarity to cutaneous mucinosis.

Pathomorphology of the skin in primary and secondary mucinosis is identical. In the epithelial sheaths and secretory sections of the sebaceous glands, inter- and intracellular edema occurs at the beginning of the process, leading to rupture of the desmosomes and loss of communication between the cells. In the future on the spot of spongiosis appear bubbles and cyst-shaped cavities. Epithelial cells with pycnotic nuclei become stellate. Here we find weakly basophilic masses that do not stain with mucicarmine red, but give metachromasia when stained with toluidine blue. Metachromasia is only partially removed by hyaluronidase, which indicates the presence, in addition to hyaluronic acid, of sulfated glycosaminoglycans. In the funnels of the hair follicles, hyper- and parakeratosis is noted, the hair is damaged or absent. Around the follicles and sebaceous glands there are always inflammatory infiltrates, which consist mainly of lymphocytes and histiocytes, sometimes with an admixture of eosinophilic granulocytes, tissue basophils and giant cells. Electron microscopic examination reveals a violation of the secretion of sebaceous glands: an increase in the volume of secretory cells and secretory vacuoles, as well as glycogen content in secretory cells. They contain unusual electronically dense material, as a result of which they acquire a spotted appearance. All cellular elements that participate in the pathological process have morphological signs of undifferentiated sebocytes.

With reticular erythematous mucinosis, mucin deposition and moderate mononuclear infiltration are found predominantly around the vessels and hair follicles. Based on the data of morphological and electron microscopic studies, DV Stevanovic (1980) concluded that plaque follicular mucinosis and REM-syndrome are the same condition.

Symptoms of the follicular mucinosis

In follicular mucinosis, a characteristic change in the root vagina of the hair follicle is observed, in which its cells are converted into a mucinous-mucous mass, which leads to the death of the hair follicle and subsequent alopecia. There are two varieties of follicular mucinosis: primary (or idiopathic, mukofaneroz), spontaneously regressing, and secondary, usually associated with lymphoproliferative diseases (mushroom mycosis, lymphomas) and other, more often systemic, skin diseases. Eruptions are represented by grouped follicular papules, less often, infiltrated, sometimes with knobby plaques. Idiopathic follicular mucinosis GW Korting et al. (1961) is considered a special form of eczematous reaction. M. Hagedorn (1979), on the basis of a frequent combination of follicular mucinosis with malignant lymphoma, refers this dermatosis to paraneoplasia.

The rashes are represented by grouped follicular papules, more rarely - yellowish-red infiltrated plaques. An erythrodermic variant is described. More often localized on the scalp, neck, in the eyebrows, less often on the trunk and extremities. There is a loss of hair, including cannabis, which can lead to total alopecia. In children, the disease manifests itself in the form of isolated hyperkeratotic follicular papular elements as large as a pinhead, scattered or grouped in limited areas of the skin. When localization on the face, especially in the eyebrows, there may be changes reminiscent of leprosy. Primary mucinosis, as a rule, spontaneously regresses, which occurs earlier, if the rashes are less common. The presence of persistent foci with increased infiltration and pruritus in linden of older ages requires the exclusion of lymphoma.

Mucinosis follicular occurs at any age, but more often in the age of 20 to 50 years. Men are sick more often than women.

Clinically, there are two forms of the disease: follicular papular and plaque, or tumor-plaque. The skin-pathological process is often located on the face, scalp, trunk and extremities. Morphological elements of the rash in the first form are numerous small (2-3 mm) follicular nodules of pinkish-cyanotic color, of a dense consistency, often with pronounced keratosis. Nodules tend to group. Often the process takes a disseminated character, while the rashes resemble gooseflesh. Most patients experience an itch of varying degrees of severity. Over time, this form can go to the plaque, or tumor-plaque.

The plaque form of follicular mucinosis develops in almost 40-50% of patients, and then the clinical picture resembles mushroom mycosis or reticulosarcomatosis of the skin. Appears one or several sharply delineated infiltrated plaques from 2 to 5 cm in diameter. Plaques, as a rule, are flat, rise above the level of the surrounding skin, with clear boundaries, their surface sometimes covered with small scales, often visible enlarged horny follicles filled with horny follicles. Plaques have a dense consistency. There is severe itching of the skin. As a result of the fusion of plaques and their further growth, tumorous-plaque foci appear, which can undergo disintegration with the formation of painful ulcers. One patient can simultaneously have papules, plaques and tumor-like elements. In half of the patients, hair loss occurs, down to total alopecia.

Reticular erythematous mucinosis (REM-syndrome) is clinically manifested by erythematous spots of irregular contours on the upper chest, neck and abdomen.

The course of the disease is long, recurrent.

[20], [21]

Forms

Distinguish primary (idiopathic) mucinosis, which develops without previous skin diseases, and secondary (symptomatic) mucinosis, which is observed in combination with mushroom mycosis, skin reticulum, Hodgkin's disease, skin leukemia and, exceptionally, chronic inflammatory dermatosis (neurodermatitis, red flat lichen, lupus erythematosus, etc.).

[22], [23], [24], [25]

Differential diagnosis

Differential diagnosis is performed with parapsoriasis (especially with plaque), numular eczema, mushroom mycosis, skin reticulum, hair keratosis, DeWerge's red hair follicle, sarcoidosis, seborrheic eczema, Lassoura-Little syndrome. It is not always easy to differentiate between primary and secondary mucinosis.

Treatment of the follicular mucinosis

In follicular-nodular form, corticosteroids are used (40-50 mg of prednisone per day). With a tumor-plaque form, the same measures as for lymphomas of the skin are carried out. External appoint corticosteroid drugs.