Basal Cell Carcinoma With Matrical Differentiation in a Transplant Patient: A Case Report and Review of the Literature

Abstract

Background: Shadow cells are characteristic of pilomatricoma, a distinct neoplasm of hair matrix differentiation. Shadow cells within an otherwise classic basal cell carcinoma (BCC) has been referred to as “BCC with matrical differentiation”. We present a case of BCC with matrical differentiation in a transplant patient. To our knowledge, none have been reported arising on the background of immunosuppression. Methods: A 58‐year‐old male cardiac transplant patient had a left hand nodule, which was excised and submitted for routine histologic review. Results: The lesion revealed multiple basaloid tumor masses. In some areas, there was peripheral palisading with stromal retraction artifact, typical of basal cell carcinoma, extending into the deep reticular dermis. The tumor also contained a population of shadow cells, similar to those in pilomatricoma, with basaloid cells in the periphery. Trichohyaline granules were identified in many of the tumor cells. These granules are a hallmark of follicular matrix differentiation. Mitoses were rare. There was no evidence of an infiltrating growth pattern. Conclusion: Basal cell carcinoma with matrical differentiation is a rare subtype of basal cell carcinoma featuring shadow cells, such as those typically seen in pilomatricoma. This tumor has not yet been reported in an immunosuppressed transplant patient.