Malignant
metastasis to the psoas muscle is rare. We report a case that clinically mimicked
psoas abscess that was subsequently proven to be from metastatic disease secondary to
adenocarcinoma of the duodenum. A 62-year-old male presented with a seven-month history of right lower quadrant
abdominal pain and progressive
dysphagia. CT scan of abdomen-pelvis revealed a right psoas infiltration not amenable to surgical drainage. Patient was treated with two courses of oral
antibiotics without improvement. Repeated CT scan showed ill-defined low-density area with inflammatory changes involving the right psoas muscle. Using CT guidance, a fine needle aspiration biopsy of the right psoas was performed that reported metastatic undifferentiated
adenocarcinoma. Patient underwent upper endoscopy, which showed a duodenal mass that was biopsied which also reported poorly differentiated
adenocarcinoma. In this case, unresponsiveness to medical
therapy or lack of improvement in imaging studies warrants consideration of differential diagnosis such as
malignancy. Iliopsoas
metastases have shown to mimic
psoas abscess on their clinical presentation and in imaging studies. To facilitate early diagnosis and improve prognosis, patients who embody strong risk factors and symptoms compatible with underlying
malignancies who present with psoas imaging concerning for
abscess should have further investigations.