Follicular mucinosis is a dermatosis based on degenerative changes in the pilosebaceal apparatus due to the deposition of mucin in it with the development of scar and non–scar type alopecia. Mucinous alopecia is characterized by itching of the skin, the appearance of small papules on the head and trunk, hyperkeratotic plaques, the formation of areas of baldness. The diagnosis is confirmed by the results of trichoscopy, morphological examination of the skin biopsy. Treatment is carried out with the help of systemic and local GCS, sulfonic drugs, retinoids, NSAIDs, phototherapy.
ICD 10
L65.2 Mucinous alopecia
General information
Follicular mucinosis (FM) is the destruction of hair follicles and surrounding sebaceous glands caused by intrafollicular accumulation of mucoproteins. The American dermatologist G. Pinkus was the first to study and describe the disease in 1957, calling it “mucinous alopecia”. In 1959, a Polish professor in the field of dermatology S. Jablonska proposed to rename dermatosis into “follicular mucinosis”, taking into account the diffuse lesion of the skin. Also in the literature, the pathology is found under the name “Brown-Falco intrafollicular sebaceous-glandular mucophanerosis”. There are two age peaks of morbidity: in 15-20 and 30-50 years. The ratio of men and women is 3:1.
Causes
The etiology of follicular mucinosis remains unclear. It is assumed that the idiopathic form of pathology may be associated with cellular immune reactions developing in response to viral and bacterial antigens (in particular, Staphylococcus aureus). Secondary follicular mucinosis occurs against the background of other dermatological or oncohematological diseases, among which there may be:
- dermatoses: atopic dermatitis, neurodermatitis, lichen planus, SLE;
- lymphoproliferative processes: skin T-cell lymphoma, leukemia, lymphogranulomatosis.
Pathogenesis
The mechanisms of development of follicular mucinosis, as well as its causes, have not been reliably established. It is likely that antigenic stimulation leads to the formation of a T-cell immune response. Acantholysis, cytolysis, and inflammation develop in the cells of the root vagina of the hair, occurring with the participation of a large number of proteolytic enzymes.
This leads to the destruction of glycoprotein complexes with the release of mucin consisting of hyaluronate and sulfated glycosaminoglycans. Its accumulation in the hair follicles and sebaceous glands triggers the destruction of the pilosebial subunit. As a result, the follicles are destroyed, scarring develops, leading to irreversible hair loss.
Histological examination of the biopsy in follicular mucinosis reveals mucin-filled cystic cavities, perifollicular lymphohistiocytic infiltrates with inclusions of eosinophils, basophils, giant cells. With fungal mycosis, atypical lymphocytes, infiltration and microabsesses of the epidermis are additionally determined.
Classification
According to the classification of the North American Society for Hair Research, the pathology is attributed to secondary nonspecific scar alopecia. Depending on the causes, two forms of mucinous alopecia are distinguished in clinical trichology: primary (idiopathic) and secondary:
1. Primary follicular mucinosis:
- acute / subacute (juvenile type of Pinkus) ‒ occurs in children and adolescents, spontaneously regresses within a few months or a year;
- chronic (adult type) ‒ develops in people over 40 years of age, is prone to persistent flow, reacts poorly to therapy;
2. Secondary follicular mucinosis:
- associated with skin diseases;
- associated with lymphoproliferative processes.
Taking into account the clinical manifestations, the following forms of follicular mucinosis are distinguished:
- follicular-papular (the primary element is the follicular papule);
- plaque (the primary element is a hyperkeratotic plaque);
- urticar-like (the primary morphological element is the urticar papule).
Symptoms
For dermatosis, the lesion of the skin of the scalp (parietal, occipital region) and the face (eyebrow area) is typical. Less often, rashes capture the neck, trunk, limbs. Follicular mucinosis can occur with different clinical variants of the rash.
In the follicular-papular form, scattered or grouped nodules with a diameter of 2-3 mm of a solid, pinkish-bluish or yellowish color with horny spikes on the surface, resembling “goose skin”, are determined.
The plaque variant of follicular mucinosis is characterized by the presence of hyperkeratotic plaques, which are infiltrated flaky foci with a diameter of 2-5 cm or more. When plaques merge, tumor-like foci form, which can erode, turn into painful ulcers.
Urticarno-like form proceeds without alopecia, passes independently. Less common with follicular mucinosis are erythematous plaques, acne rash, vesicles, purpura. One patient may have different types of rash at the same time.
Regardless of the type of follicular mucinosis and the type of rash, intense itching, burning of the skin, hair loss (mucinous alopecia) is noted in the lesions. In the early stages, baldness is potentially reversible, but with a far-reaching process, cicatricial alopecia develops.
In places of baldness (on the head, in the area of eyebrows, mustache and beard, on the chest of men, on the limbs, in the pubic area), gaping holes of hair follicles are visible, when pressed, transparent mucus is released from the mouths of the VF. Anhidrosis is possible.
Complications
The course of follicular mucinosis can be different: in the acute form, spontaneous regression of the rash and restoration of hair growth is possible, in the chronic form, a slow progression of the disease occurs, hair in the foci of baldness does not grow back. The development of total alopecia is possible. Due to hair loss, the disease causes severe psychological discomfort, and constant itching causes painful physical sensations.
Persistent or progressive nature of follicular mucinosis may indicate fungal mycosis (in adults) or Hodgkin’s lymphoma (in children), therefore, such patients require regular monitoring by an oncodermologist and repeated skin biopsies.
Diagnostics
With complaints of itching and hair loss, patients turn to a dermatologist-trichologist. During the initial visual examination of the skin, irregular-shaped areas of alopecia with hyperemia and small-plate peeling are revealed. To clarify the diagnostic hypothesis, the following studies are conducted:
- Trichoscopy. When examined under multiple magnification, the mouths of hair follicles in the foci of baldness are not visualized, areas of fibrosis are visible.
- Skin biopsy with histology. The pathomorphological picture corresponding to follicular mucinosis is characterized by the presence of lymphocytic infiltrates, mucin deposits. Additionally, a biopsy of the lymph nodes may be required.
- Laboratory tests. To exclude the different nature of skin itching and baldness, microscopic examination for pathogenic fungi is performed. Urinary test, antinuclear antibodies, LE cells are examined, treponemal tests are performed.
Differential diagnosis
The range of diseases that require exclusion in the examination for dermatosis includes:
- focal alopecia;
- broca ‘s pseudopelada;
- brow scarring erythema;
- lichenoid tuberculosis;
- discoid lupus;
- lichen (Vidal, red flat, spike-shaped, shiny, red bran-shaped);
- scleromyxedema (myxedematous lichen);
- sycosis;
- syphilis;
- skin mycoses;
- plaque parapsoriasis.
Treatment
In children, the disease, as a rule, does not require medical treatment and disappears on its own. In secondary forms of follicular mucinosis, the treatment of the underlying disease (dermatosis, lymphoproliferative tumor) is primarily carried out. In other cases, the following activities are shown:
- Systemic therapy. The first-line drugs are systemic glucocorticoids. NSAIDs, anti-leprosy, antimalarial agents, vasoprotectors, microcirculation activators, interferon preparations are also used.
- Local pharmacotherapy. Locally, solutions of GCS are injected into the affected foci. In some cases, with follicular mucinosis, the application of hair growth stimulants, zinc preparations, fusidic acid can be effective.
- Phototherapy. To eliminate itching, peeling, reduce the number of plaques and the area of the lesion, PUVA therapy, ultraviolet UVA-1 therapy, Bucca therapy are carried out.
Prognosis and prevention
Benign follicular mucinosis has a favorable course. Nevertheless, patients with an established diagnosis require long-term follow-up by a dermatologist and oncologist, dynamic morphological control. When follicular mucinosis is combined with malignant skin lymphoma or lymphogranulomatosis, the prognosis is unfavorable. Given the unclear etiopathogenetic mechanisms, primary prevention is not carried out. It is recommended to sanitize chronic infectious foci, treat background dermatopathies in a timely manner.
