Atypical umbilical endometriosis: Microscopic and immunohistochemical characterization

Introduction

Atypical endometriosis is considered a precursor lesion to cancer associated with endometriosis. Two types of atypical endometriosis have been proposed: an architectural type with a higher risk of malignancy and a cytological type with a lower potential for malignancy.

Main symptoms and/or clinical findings

A 37-year-old Caucasian woman presented with umbilical bleeding coinciding with menstruation. On physical examination, two small, bluish lesions were observed in the umbilical scar.

Primary diagnosis

This clinical case is of interest because it describes a lesion of atypical architectural endometriosis located in the navel.

Therapeutic interventions and results

The microscopic and immunohistochemical characteristics of the lesion were examined. The presence of nuclear stratification, hyperchromatism, and pleomorphism were observed as microscopic qualities. In terms of the immunohistochemical panel, the degree of cell proliferation was analyzed using Ki 67, BAF250a was used as the surrogate marker of ARID 1A, inflammation was assessed through COX, and estrogen and progesterone receptors were examined. The results showed increased cellular activity, the presence of inflammation, and no mutation of the ARID1a gene, with moderate cell proliferation.

Conclusion

Umbilical endometriosis is rare, and while malignancy is infrequent, it is possible. For this reason, a complete anatomopathological study including an immunohistochemical panel should be performed to diagnose atypical endometriosis.