Abstract:

A 69-year-old female with a history of a solid lung mass and a hypo-attenuating pancreatic mass presented to her doctor for enlarging right inguinal masses. Excisional biopsies of the 2.0 x 2.0 cm and 1.6 x 0.7 cm right inguinal lesions revealed poorly differentiated neoplasms on histopathologic examination. Immunohistochemical studies (IHC) for pancytokeratin, CK7 and calretinin were positive but p40, SOX-10, CK20, TTF-1, PAX8, ERG, GATA3, ER, WT-1, MOC31 and mammaglobin were negative. At this time the differential diagnosis included poorly differentiated carcinoma or mesothelioma. Given the IHC findings, a primary lung tumor was deemed unlikely. A diagnosis of a mesothelioma was considered but was unlikely due to the rapid progression of the lesions. A lung biopsy performed 1.5 weeks later revealed a malignant neoplasm more characteristic of adenocarcinoma with mucinous features. Focal areas demonstrated poorly differentiated carcinoma similar to the skin lesions. IHC studies were positive for CK 7, CK 19, CK 20 (focally), and CA 19-9, suggesting metastasis from the pancreatobiliary tract or upper gastrointestinal system. With the addition of these new findings, mesothelioma was finally ruled out. Cutaneous metastasis are present in ~5% of patients with visceral malignancies. The chest is the most common site of metastasis accounting for ~28% of cases. The pelvis is the second-rarest site of metastasis accounting for 6% of cases. Metastatic disease should be suspected in inguinal lesions with characteristic histopathological findings and associated visceral lesions. Correlation with IHC, radiology and lesion onset is important in determining an accurate diagnosis.

Financial Disclosure:
No current or relevant financial relationships exist.

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Ayodele Adelanwa, MD