Carcinoma of unknown primary: Molecular tumor board‐based therapy

Abstract

A 36-year-old woman presented to an outside hospital with abdominal pain in July of 2021. A computerized tomography (CT) scan of the abdomen and pelvis showed multiple, hypodense lesions within the left hepatic lobe that were concerning for metastatic disease. The largest liver lesion (3.1 × 2.2 cm) was bi-opsied, and pathology was consistent with meta-static, moderately differentiated adenocarcinoma. Immunohistochemistry (IHC) stains performed for further characterization of the tumor were positive for cytokeratin 7 (CK7) and CDX2 and negative for CK20, HepPar-1, Napsin A, and GATA-3, consistent with ad-enocarcinoma. The differential diagnosis included primary cholangiocarcinoma versus metastatic car-cinoma of upper gastroesophageal or pancreaticobi-liary origin. Of note, it was also suspected that the patient had amoebiasis, and she was on treatment with antibiotics. She later transferred her care to our university hospital. A follow-up CT scan of the abdomen and pelvis performed a few weeks after the initial presentation demonstrated hypodense liver lesions involving the right and left lobes as well as peripan-creatic and gastrohepatic lymph nodes, which were suspicious for malignancy. Because the liver biopsy could not identify the primary tumor conclusively, subsequent endoscopic ultrasound and fine-needle aspiration of the peripancreatic lymph node were performed almost a month after the initial presentation.