Squamous cell carcinoma with enteric adenocarcinomatous differentiation

A Case of Biphenotypic Adnexal Carcinoma With Bowenoid and Basaloid Features: Focus on the Expression of SOX9 and Wnt Signaling Pathway Molecules, Including CDX2

ABSTRACT

An 87-year-old woman presented with a pedunculated nodule of 1.2 × 1.2 × 0.6 cm on her left cheek. Microscopic examination of the lesion revealed bowenoid and rosette-like basaloid components, resembling Bowen disease and neuroendocrine carcinoma, respectively. Immunohistochemically, both components were positive for Wnt signaling pathway molecules-nuclear/cytoplasmic beta-catenin, lymphoid enhancer binding factor 1 (LEF1), and caudal type homeobox 2 (CDX2)-and the adnexal marker SRY-box transcription factor 9 (SOX9). Unlike neuroendocrine tumors and basal cell carcinomas, the basaloid component in the present case was negative for chromogranin A, INSM1, synaptophysin, and p40. Previously reported cases of similar CDX2-positive lesions were diagnosed as squamous cell carcinoma with enteric adenocarcinomatous differentiation and basaloid cutaneous carcinoma with a primitive cytomorphology. However, the lesion in the present case was simultaneously positive for SOX9, indicating adnexal differentiation. In particular, the expression of multiple Wnt signaling pathway molecules indicates follicular differentiation despite the absence of morphological follicular features, such as shadow cells. Moreover, shared immunopositivity for SOX9, CDX2, nuclear/cytoplasmic beta-catenin, and LEF1 by both bowenoid and basaloid components indicated that the bowenoid component did not represent Bowen disease but a part of the adnexal tumor, and that the basaloid component was not a tumor-to-tumor metastasis. After complete excision, no recurrence has been observed for 5 months. The findings of the present case expand the histological spectrum of cutaneous adnexal tumors with follicular immunophenotypic differentiation.

CDX2 expression in primary skin tumors-case series and review of the literature

CDX2 expression characterizes tumors of gastrointestinal origin, including those of intestinal-type differentiation. In dermatopathology, CDX2 expression is reported in 4 settings: cutaneous metastases from carcinomas of intestinal origin or differentiation, extramammary Paget's disease associated with an underlying colorectal or urothelial tumor, pilomatricomas and pilomatrical carcinomas, and rare primary cutaneous (adeno)squamous carcinomas with intestinal immunophenotype. Over 4 years (10/2017-10/2021), 252 dermatopathology cases with CDX2 immunostain were reviewed, revealing 46 cases with confirmed positive staining. Among them, 11 cases confirmed as primary nonintestinal type cutaneous carcinoma with definitively positive CDX2 nuclear staining were further studied. All cases demonstrated basaloid morphology with atypia, variable necrosis, and brisk mitotic activity. Cases 1-5 had heterogeneous features that cannot be further classified, including 2 cases with neuroendocrine or pseudoglandular/pseudopapillary features, and 1 case with human papillomavirus high-risk E6/E7 ISH positivity. In cases 6 through 11, the diagnosis of pilomatrical carcinoma was supported morphologically. This study substantiates the association of CDX2 with pilomatrical carcinoma. In addition, CDX2 positivity was observed in a subset of basaloid cutaneous carcinomas of ambiguous classification. However, this finding also raises a diagnostic pitfall in clinical diagnostic specificity of the CDX2 immunostain in skin cancers, which can be observed in rare while heterogeneous subsets of primary cutaneous carcinomas with primitive cytomorphology.

Cutaneous Adenosquamous Carcinoma of the Scalp With Intestinal Phenotype

Cutaneous adenosquamous carcinoma is a mixed, squamous and glandular, rare malignant tumor of the skin characterized by a mixed, squamous, and glandular differentiation. Few cases of this tumor have been so far reported, and even fewer have been thoroughly studied by immunohistochemistry. We report here an exceptional case of cutaneous adenosquamous carcinoma which showed immunohistochemically features of intestinal differentiation, namely because of the expression of keratin 20 and CDX2, a marker of gastrointestinal tumors.