title: Hypodermal decidualized endometrioma with aberrant cytokeratin expression. A lesion mimicking malignancy.
abstract: Decidualized endometrioma is a pseudoneoplastic lesion that may appear as a solitary nodule in the hypodermis, simulate a malignant epithelioid tumor, and can represent a diagnostic challenge. A 36-year-old woman delivered a full-term baby by cesarean. At the immediate puerperium, she complained of a subcutaneous nodule measuring 2.5 cm, underneath a previous caesarean scar from the former full-term delivery 3 years earlier. Histologic features included a nodular growth pattern of large monomorphic epithelioid cells showing diffuse positivity for cytokeratin (AE1/AE3, 18), human placental lactogen, and CD10 and focal positivity for inhibin alpha. The main differential diagnoses include trophoblastic neoplasia and deciduoid mesothelioma. Good clinicopathological correlation is essential for the correct diagnosis. Immunohistochemical stains can be misleading. An important clue is the combination of large decidualized cells and lumens lined by flat or low cuboidal cells that are atrophic endometrial glands. This lesion has a benign behavior.
authors.affiliation: Department of Anatomical Pathology, Marques de Valdecilla University Hospital, Medical Faculty, University of Cantabria, Santander, Spain. soler@bellvitgehospital.cat
authors.forename: José Fernando
authors.initials: JF
authors.lastname: Val-Bernal
authors.forename: Daniel
authors.initials: D
authors.lastname: Val
authors.forename: Fernando
authors.initials: F
authors.lastname: Gómez-Aguado
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Corcuera
authors.forename: María Francisca
authors.initials: MF
authors.lastname: Garijo
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D004715:Endometriosis / Q000378:metabolism / Q000473:pathology*; D005260:Female; D031901:Gestational Trophoblastic Disease / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000096:biosynthesis*; D008654:Mesothelioma / Q000473:pathology; D011247:Pregnancy; D012867:Skin / Q000473:pathology*
chemical_list: D007633:Keratins