Carcinoma of Unknown Primary

Abstract

A 74-year-old woman presented with seizures and change in mental status. An MRI of the brain revealed a single ring-enhancing 1.6 ?× ?2.1 ?× ?2.1 cm mass with surrounding prominent edema in the deep white matter of the left posterior parietal region. The radiological differential diagnosis was a high grade glioma versus a metastatic malignancy. She had been debilitated all of her life due to brain damage during birth, with related hearing loss and mental retardation. There was no significant family history. On admission, her vital signs were unremarkable and no palpable masses were identified in the body, including her breasts. The laboratory data were unremarkable. She underwent craniotomy for gross total excision of the tumor. Histologic examination showed a metastatic, poorly differentiated adenocarcinoma with massive necrosis. Immunohistochemically, the tumor cells were diffusely and strongly positive for cytokeratin 7 (CK-7) (basic cytokeratin found on specific epithelia, such as breast, lung, and gastric cancers) and mammaglobin (breast marker); focally positive for p63 and CA125 (urothelial markers), CD10 and PAX-2 (renal cell markers), and gross cystic disease fluid protein (GCDFP)-15 (breast marker); and negative for CK-20 (colonic and urothelial marker), CDX-2 (colonic marker), CA19-9 (pancreatic marker), TTF-1 (thyroid and lung marker), GFAP (glial marker), S-100 protein (neural and melanoma marker), RCC (renal cell marker), and WT-1 (ovarian marker). As a metastatic evaluation, a CT scan of the thorax, abdomen, and pelvis was performed, and revealed no suspected primary or secondary malignancies. The patient did not cooperate for mammography. By bilateral breast ultrasonography, a 1.5 cm solid mass was detected in her left breast. Her family decided against further invasive procedures for diagnostic purposes.