A 67-year-old Japanese female presented with a left buttock tumor, which had been first detected approximately 1 year earlier, and had recently gradually enlarged.
Physical examination revealed a relatively well-circumscribed skin-colored tumor with hyperkeratosis, measuring 43 x 38 mm in diameter, in her left buttock.
The biopsy specimen revealed Bowen’s disease (squamous cell carcinoma in situ), and subsequently, total resection of the tumor was performed.
Histopathological study of the resected specimen revealed proliferation of atypical squamous cells in the entire layer of the acanthotic epidermis accompanied by hyperparakeratosis (Figure 1A).
These atypical squamous cells had enlarged and hyperchromatic nuclei (Figure 1B), and multinucleated atypical squamous cells were also present.
Mitotic figures were scattered and present in the upper portion of the epidermis.
Atypical mitotic figures were also observed (Figure 1B).
No invasive neoplastic growth was noted (Figure 1A).
Approximately 95% of the lesion was composed of the above-mentioned Bowen’s disease (squamous cell carcinoma in situ), and superficial sebaceous carcinoma was present in the central area of the lesion.
This latter component was composed of proliferation of nests of atypical cells with vacuolated clear cytoplasm and large nuclei containing conspicuous nucleoli (Figure 1C, ​,1D).1D).
Sebaceous carcinoma had invaded into the superficial reticular dermis (Figure 1C).
Moreover, atypical cells containing vacuolated cytoplasm were present within the lesion of Bowen’s disease adjacent to the sebaceous carcinoma (Figure 1E).
Immunohistochemical studies were performed using an autostainer (Ventana) by the same method as previously reported [9-12].
Epithelial membrane antigen (EMA), cytokeratin 7, and adipophilin were expressed in the sebaceous carcinoma component, but not in Bowen’s disease (Figure 2A).
Androgen receptor was also expressed in some of the tumor cells of the sebaceous carcinoma, but not in Bowen’s disease.
Moreover, atypical vacuolated cells within the lesion of Bowen’s disease were also positive for adipophilin (Figure 2B).
Overexpression of p53 protein was observed in both the sebaceous carcinoma and Bowen’s disease.
Accordingly, an ultimate diagnosis of sebaceous carcinoma associated with Bowen’s disease was made.