Diagnostic Pitfalls Related to Morular Metaplasia in Endometrioid Carcinoma: An Underestimated Issue

Abstract

Here, we present a case that highlights the crucial pitfalls related to the presence of morular metaplasia (MM) in endometrioid carcinoma, which are insufficiently recognized in the routine pathology practice. A 45-year-old woman underwent hysterectomy with rectosigmoidectomy due to a 11-cm mass involving uterus, right ovary, and rectosigmoid colon. Histologically, the lesion appeared as a predominantly solid carcinoma with a minor glandular component. Results of the first immunohistochemical analysis suggested a colorectal origin (PAX8-, CK7-, WT1-, hormone receptors-, and CDX2+ in the absence of mucinous features). Subsequent immunohistochemistry (nuclear β-catenin+, CD10+, and low ki67 in the solid areas) supported a diagnosis of endometrioid carcinoma with diffuse MM. This case remarks that morphological and immunohistochemical features of MM may conceal the glandular architecture and the typical immunophenotype of endometrioid carcinomas. Acknowledging the diagnostic issues related to MM appears crucial to avoid misdiagnosis and inappropriate patient management.

Endometrioid Squamous Proliferations of the Endometrium Express Alpha-Methylacyl-CoA Racemase (P504s)

“…(22)(23)(24) Most SMMs lack estrogen receptor and p63 expression but tend to be positive for CDX-2, CD10, and beta-catenin. (25)(26)(27) This immunoprofile is in contrast to typical squamous elements, which are usually positive for CD10 and p63. (28) More recently, SATB2 was described as a positive marker in SMM, (29) and based on the results from our study, AMACR is another IHC consistently expressed in SMM and NMSM.…”

Pilomatrix-like High-Grade Endometrioid Carcinoma of the Ovary: Case Report, Literature Review, and Differential Diagnosis

“…Moreover, the presence of ghost cell keratinization is not uncommon in morular metaplasia. In these cases, immunohistochemistry should be carefully assessed, as morular metaplasia typically shows nuclear β-catenin and CDX2 expression and may be negative for Müllerian markers [ 15 ]. It should be noted that morular metaplasia is characterized by cells with bland nuclear features and wide eosinophilic cytoplasm, while the cells of PiMHEC are basaloid with high-grade features and high nucleus-to-cytoplasm ratio.…”