Objective: To describe the computed tomography (CT) features at diagnosis and after treatment of adenocarcinoma of unknown primary (ACUP) mimicking lymphoma of the mediastinum.
Methods: Fifteen patients with pathologically proven ACUP and with primarily mediastinal involvement were initially referred to the Hematologic Department of our institution with a suspected diagnosis of lymphoma, and accounted for our study population. Presenting symptoms and baseline biological values were analyzed. All thoraco-abdominal CT studies were reviewed for the location and size of the mediastinal involvement and associated findings. Follow-up chest CT was performed in 14 patients after radiotherapy, chemotherapy or surgical treatment.
Results: The most frequent CT feature was a large anterior and middle mediastinal mass (67%), with no calcification. Associated findings included the presence of lung nodules (40%), compression of large mediastinal vessels (33%) and pleural effusion (27%). Follow-up CT, performed in 14 cases, suggested partial or complete responses in 7 patients (50%) 4 weeks after the treatment onset.
Conclusions: Mediastinal ACUP is a differential diagnosis of large mediastinal masses and is frequently associated with lung nodules and mediastinal vascular compression.