Psoas Muscle Infiltration Masquerading Distant Adenocarcinoma

Abstract

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.

Psoas as an Unusual and Overlooked Place for a Metastatic Tumor

“…Repeated CT scan showed ill-defined low-density area with inflammatory changes involving the right psoas muscle. In this report, a fine needle aspiration biopsy of the right psoas was performed by CT guidance to obtain the histopathologic diagnosis [7]. Singh et al reported a 68-year-old male patient presented with fever, groin pain, leukocytosis and azotemia mimicking pyelonephritis that was subsequently proven to be from a diffuse, large, B-cell lymphoma by fineneedle aspiration cytology and biopsy from the lesions.…”

Pulmonary Adenocarcinoma Presenting as Paraspinal Muscle Metastatic Mass

“…The most common metastatic sites of lung cancer are the adrenal glands, liver, bone, and brain—as seen with the renal and liver lesions discovered in our case [ 7 ]. Frequent sites of skeletal muscle metastatic involvement, specifically in lung cancer, include the thigh, iliopsoas, and paraspinous muscles, though lesions in the orbit and pectoral muscles have been described [ 4 , 8 – 11 ].…”

“…A subgroup analysis revealed that masses of pulmonary origin had low central attenuation with rim enhancement as the most common finding on CT [ 13 ]. Correlation with FDG-PET is recommended in all patients with a history of malignancy or a suspicion lesion [ 3 , 8 , 9 , 18 ]. Biopsy of these masses is mandatory for proper diagnosis and further management [ 6 , 9 , 19 ].…”

Leg Pain Disclosing Lung Cancer: A Case Report and Review of the Literature

“…Those cases found during the staging for a known primary cancer were excluded. We found only a few reported cases [4][5][6][7][8][9][10] ; a summary is shown in Table 1.…”

“…Among these cases, only the reports by Tonelli et al 10 and Gharaibeh et al 5 indicated “crural neuralgia” and “groin and anterior thigh pain,” respectively, as the initial symptoms of psoas muscle metastasis, disclosing a hidden primary cancer. However, these reports lacked an electrodiagnostic verification of femoral neuropathy.…”