Pathomorphological analysis of the qualitative composition of the inflammatory infiltrate around the pilosebaceous unit of the scalp in perifolliculitis capitis abscedens et suffodiens

Abstract

Perifolliculitis capitis abscedens et suffodiens (PCAS) or Hoffman’s disease is considered a rather rare therapeutically complex purulent skin disease of unknown etiology. An active search for information regarding the qualitative and quantitative composition of the inflammatory infiltrate in PCAS, which could become a source for understanding the pathogenesis of this disease, revealed a lack of studies using the immunohistochemical staining method and authoritative recommendations on the interpretation of the obtained histological changes in punch biopsies for further treatment.

The aim of the work is to investigate the peculiarities of the location and number of CD20+, CD3+ cells and their populations of CD4+ / CD8+ T-lymphocytes of the inflammatory infiltrate around the pilosebaceous unit of the scalp in PCAS.

Materials and methods. In the work, the material of 12 male patients with a diagnosis of undermining abscessing perifolliculitis of the head (Hoffman’s disease), aged from 20 to 51 years, the average age was 35.50 ± 11.54 years, and 5 samples of clean resection edges (conditional norm) of benign nevi of the scalp were examined. Heads of men aged 34 to 48 years, the average age was 32.10 ± 9.42 years (the control group compared with the research group did not show a statistically significant difference, p > 0.05). Immunohistochemical examination was performed according to the protocols of TermoScientific (TS) with primary antibodies against B-lymphocytes (CD20, RTU), T-lymphocytes (CD3, RTU), T-helper / T-regulatory cells (CD4, RTU), T-cytotoxic lymphocytes (CD8, RTU). Lab Vision Quanto imaging system (TS, USA) was used with detection of the reaction using DAB Quanto Chromogen (TS, USA).

Results. The pathohistological pattern of damage to the pilosebaceous unit of the scalp in PCAS is characterized by a deep inflammatory infiltrate located at the level of the reticular dermis or hypodermis, the development of perifolliculitis in the direction of the formation of deep abscesses and the destruction of follicles with the formation of lymphoplasmacytic granulomas or granulomas with giant cells, obligatory hyperplasia of the sebaceous apparatus glands that open into the hair follicle. Given the bactericidal and fungicidal properties of each fat that actively produces sebaceous glands, their hyperplasia in PCAS may be an indirect confirmation of an adaptive response to commensal biological factors in the development of this pathology. Accumulation of CD20 (+) cells in the outer root epithelial sheath and CD3 (+) cells in the outer and inner root epithelial sheath around the shaft of the hair follicle bud, which is a source of stem cells for reparative regeneration of the epidermis and epithelization of the wound surface, is likely to lead to long-term healing period and alopecia in PCAS. A high density of infiltration by CD20 (+) and CD3 (+) cells in the area of the excretory ducts of the sebaceous glands and CD3 (+) cells in the area of the secretory departments of the sebaceous glands probably leads to hyperplasia of the sebaceous gland apparatus as a reactive process of reparative regeneration in PCAS.

Conclusions. The predominance of CD4⁺–T-helpers, compared to CD8⁺–T-cytotoxic lymphocytes, among the CD3 (+) cells of the inflammatory infiltrate in PCAS indicates the superiority of the effector mechanisms of the immune response, which as a result leads to the activation of macrophages, neutrophils and CD20 (+) B-lymphocytes, which is reflected in the accumulation of these cells in the foci of chronic inflammation around pilosebaceous units of the scalp. The strong humoral response that develops in PCAS as a result of the activation of CD20 (+) B-lymphocytes through effector CD4⁺–T-helpers is effective in the fight against extracellular microorganisms and their toxins and works most powerfully against microorganisms that have a capsule of polysaccharides and lipids, which become a target for antibodies produced by plasma cells, while the smaller number of CD8⁺–T-cytotoxic lymphocytes are able to respond only to protein antigens. Thus, the study of the features of the immune response in PCAS indirectly helps to clarify the spectrum of etiological factors for improving the treatment strategy.