Case Report

A 48-year-old male patient, with controlled schizophrenia, referred to the hospital reporting the appearance of three nodular lesions on the posterior left side of the neck, right side of the scalp in the temporal region and left occiptal region of the scalp, noticed 1 year ago.

The tumors showed areas of tessiu with acantholysis and queritinized center, which is representative of trichilemmal differentiation. The histological findings were consistent with proliferinting trichilemmal tumor.

The complete cirugical exeresis was performed in hospital. The histopatologic exam revealed an intradermic proliferation with lobular architecture and irregularities, formed by epithelial eosinophilic cluster, with pleomorphism and nuclear atypias forming a fibrous pseudocapsule.

Discussion

The proliferating trichilemmal tumor is a rare and pseudomalignant lesion as can be seen in literature reviews (Table 1), described in 1966 by Wilson Jones.

Pseudomalignity is due to histological presentation, which may be similar to squamous cell carcinoma. The occurrence mainly affect female patients (more than 90% of cases) and elderly women. The most affected

regions of the body involve areas with greater exposure to the sun's rays and which have a higher density of hair follicles since it evolves from the hair follicle isthmus such as the scalp, for example, but can also develop in other areas like the trunk and neck. Its pathogenesis is unknown; however, in some cases there is the presence of Human Papilloma Virus (HPV), raising the hypothesis that there is some relationship between the presence of the virus and the development of the tumor. Clinically, it manifests as a solitary, well-circumscribed, nodular tumor, of variable size and slow growth, which may present inflammatory signs. The lesion area commonly presents alopecia, as well as atrophy or ulceration of the edges. Diagnostic confirmation is done by anatomopathological examination. Macroscopically, the lesions are multinodular and in the superficial section, the cysts are filled with keratin and calcifications. Microscopically, it is presented as a well-defined solid-cystic mass that affects the dermis and can extend to the subcutaneous tissue. The characteristic histological marker is the presence of trichilemmal keratinization, in which there is an abrupt transition from epithelial nucleated cells to keratinized anucleated cells and, also, there is absence of the granular layer. Other exams, such as magnetic resonance and ultrasonography, are important for differential diagnosis, prognosis and adequate treatment. The differential diagnosis includes several entities, among then malignant proliferation and squamous cell carcinoma. Treatment consists of resection with safety margins. The prognosis in most cases is optimistic but there are caveats for cysts that present cell atypia as a histopathological finding due to the possibility of malignant evolution.

Tables

References

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