Ultrasound guided biopsy of the thigh mass was undertaken.

Histology

Macroscopic: Two cores up to 14 mm in length. Microscopic: The needle core biopsies show extensive infiltration by an invasive, moderately differentiated adenocarcinoma. There are some cytoplasmic vacuoles but no true clear cell changes present. There is no associated microcalcification. Immunohistochemistry shows diffuse strong positive staining with cytokeratin 7. Cytokeratin 20 shows focal and weak positive staining only. CEA, CD10 and TTF-1 are all negative. The morphological appearances and immunohistochemical profile indicate metastatic adenocarcinoma. The most likely primary sites of origin would include the pancreas, hepatobiliary tract and upper gastrointestinal tract, including the esophagus. The recent endoscopic examination results are noted: Two separate biopsy samples both show features of columnar lined esophagus (Barrett esophagus) with high-grade glandular dysplasia features suspicious of invasive neoplasia.

Diagnosis: metastatic adenocarcinoma.