Bowen disease with invasive mucin‐secreting sweat gland differentiation: Report of a case and review of the literature

Bowen's Disease

Bowen's disease (BD) is an in-situ squamous cell carcinoma of epidermis. The etiology of BD is multifactorial with high incidence among Caucasians. BD is common in photo-exposed areas of skin, but other sites can also be involved. Lesions are usually solitary. The morphology of BD differs based on age of the lesion, site of origin, and the degree of keratinization. BD is considered as the "lull before the storm," which precedes an overt squamous cell carcinoma. Histopathology is the gold standard diagnostic modality to confirm the diagnosis. Immunohistochemistry, dermoscopy, and reflectance confocal microscopy are the adjuvant modalities used in the diagnosis of BD. The treatment depends on various factors like site, size, immune status, patient's age, esthetic outcome, etc. The available therapeutic modalities include topical chemotherapy, surgical modalities, light-based modalities, and destructive therapies. It requires a combined effort of dermatologist, oncosurgeon, and plastic surgeon to plan and execute the management in various presentations of BD.

Porocarcinoma with areas of mucinous differentiation suggesting multilineage differentiation

Porocarcinoma is an infrequent malignant adnexal carcinoma, with some histopathological variants described, such as the clear cell, the sarcomatoid or the pigmented porocarcinoma. We report an invasive porocarcinoma showing areas of tumor cells floating in prominent dermal mucin, simulating mucinous carcinoma, that we consider a new histopathological variant of porocarcinoma. We report a 74-year-old male with previous history of multiple basal cell carcinomas that presented a nodule on his left temple. Histopathologic study showed a large ulcerated multilobular tumor composed of thickened cords of cells emanating from a hyperplastic epidermis and showing a mixed infiltrative and pushing pattern in the dermis. Poroid differentiation was observed in most of the neoplasm, both in intraepidermal and dermal invasive component. Within the neoplasm a prominent area where these small nests with clear formation of ducts were floating in mucinous pools with few septa intermingled was observed, simulating a primary cutaneous mucinous carcinoma. Cytology, immunohistochemistry and the presence of both neoplastic areas as closely related and with multiple points of connectivity favors the consideration of a composite tumor in this peculiar case. Other differentials are discussed.

Bowen disease with matrical differentiation: Report of an exceptional histopathologic presentation

Matrical differentiation is the distinctive feature of pilomatricoma and other purely matrical adnexal neoplasms; additionally, foci of matrical differentiation have been also described in hybrid cysts of Gardner syndrome, as well as in a wide variety of benign and malignant cutaneous tumors, including basal cell carcinoma. We report an exceptional case of Bowen disease exhibiting multiple foci of matrical differentiation, as confirmed by means of immunohistochemical studies. Several types of divergent, non-squamous differentiation have been exceptionally reported in cutaneous squamous cell carcinoma in situ (cSCCIS), including sebaceous, mucinous/glandular, poroid, tricholemmal, and neuroendocrine differentiation; matrical differentiation may be added to this list. Our findings further emphasize the undifferentiated nature of neoplastic cells in cSCCIS.