Infarcted Adenomatoid Tumor: A Diagnostic Challenge

Dreyer D, Fine E, Unger P, Nicolaou N: Infarcted Adenomatoid Tumor: A Diagnostic Challenge. Meeting Abstract, American Journal of Clinical Pathology, Vol. 146, Issue Suppl. 1, September 2016

(September 1, 2016) Infarcted adenomatoid tumors often pose diagnostic difficulty due to morphological features such as cytologic atypia and mitoses. This appearance might suggest the possibility of a malignant neoplasm leading to more aggressive therapy. We present an unusual case of an infarcted adenomatoid tumor with atypical features.

A 32-year-old man presented with a palpable scrotal mass, which corresponded to a 1.2 cm right epididymal lesion on ultrasound. After one year, during an episode of acute epididymitis, the nodule enlarged to a size of 2 cm but regressed to its original size following antibiotics. Subsequently, the nodule and the inferior border of the epididymis were excised. Grossly, the specimen consisted of a well demarcated, firm, gray-white nodule measuring 1.7 cm.

Microscopically, the specimen consisted of a cellular mesothelial neoplasm with a biphasic solid growth pattern and a central area of coagulative necrosis and adjacent stromal reaction. The neoplastic cells had an increased nuclear:cytoplasmic ratio, frequent prominent nucleoli, occasional mitoses, and numerous interspersed lymphocytes. Positive immunostains included CAM5:2, pankeratin, vimentin, D2-40, calretinin, and weak WT1. Although initially interpreted as a mesothelioma, the final diagnosis was infarcted adenomatoid tumor with atypical features, and close clinical follow-up was recommended.

Adenomatoid tumors with a solid growth pattern (as opposed to a more typical angiomatoid pattern) are rare and can be mistaken for an infiltrating malignancy. Tumor infarction is also uncommon. Our case is an example of these two diagnostic problems occurring simultaneously. Reasons for infarction in an adenomatoid tumor can include large size or trauma. Most likely in our case, it was the latter Given the singularity and lack of definitive invasion into the adjacent tissue, malignant mesothelioma was ultimately ruled out and a diagnosis of infarcted adenomatoid tumor with atypical features was rendered.