Cribriform tumors of the skin: CD38 expression distinguishes from histologic mimics in a multi-institutional series.

Abstract

Cribriform tumor of the skin (formerly primary cutaneous cribriform carcinoma/primary cutaneous cribriform apocrine carcinoma) is a rare adnexal neoplasm of uncertain malignant potential. Recent studies have identified recurrent co-deletion of the long arm of chromosomes 6 and 9 and CD38 overexpression as potential diagnostic features, but their sensitivity and specificity remain incompletely defined. We identified 11 cribriform tumors with classic morphologic features, including several previously reported molecular characterized cases and additional unpublished cases, from multiple institutions. CD38 immunohistochemistry was performed on all tumors and compared with a panel of morphologic mimics, including adenoid cystic carcinoma (n = 8), digital papillary adenocarcinoma (n = 8), eccrine/apocrine adenomas (n = 7), hidradenoma (n = 2), and endocrine mucin-producing sweat gland carcinoma (n = 3). SNP array analysis was available in nine cases. Patients had a median age of 47 years with a slight female predominance (64%). Tumors commonly involved the extremities and ranged from 0.3 to 2.0 cm. Histologically, all cases demonstrated a well-circumscribed dermal neoplasm of bland epithelial cells arranged in cribriform architecture with characteristic thread-like intraluminal bridging, without high-grade features. CD38 expression was identified in 9/11 cases (82%), typically with moderate-to-strong diffuse cytoplasmic staining. All morphologic mimics (n = 28) were CD38 negative. Recurrent chromosomal deletions involving 6q and/or 9q were identified in 7/8 (88%) successfully tested cases. Two morphologically classic cribriform tumors lacked CD38 expression, including one with confirmed 6q/9q codeletion, while one CD38-positive case lacked detectable genomic copy number alterations. These findings further support cribriform tumors as a molecularly distinct, low-grade adnexal neoplasm characterized by recurrent 6q/9q deletions and frequent CD38 expression. CD38 appears to be a useful adjunctive diagnostic marker with high specificity among the selected mimics tested, although its sensitivity is incomplete, and absence of staining does not exclude the diagnosis.