Pyomyositis as an Unusual Presentation of Colonic Adenocarcinoma

Pyomyositis has been described in association with hematological malignancies. It is rarely associated with solid cancers, particularly colorectal carcinoma. Colorectal carcinoma can present with local or systemic abscesses by causing perforation of the colonic mucosa, followed by local or hematogenous spread of infection.

A 68-year-old male with a history of hypertension and type II diabetes mellitus presented to the emergency department with a 3-day history of left thigh pain. Magnetic resonance imaging of the thigh showed extensive intramuscular edema in the left thigh adductor and psoas muscles consistent with pyomyositis. An urgent debridement and irrigation of the left thigh revealed pan-sensitive Escherichia coli and Streptococcus viridans. Due to the suspicion of a gastrointestinal or genitourinary source of infection, computed tomography of the abdomen and pelvis showed an apple-core lesion along the mid-distal segment of the descending colon. Colonoscopy and biopsy confirmed the diagnosis of colonic adenocarcinoma. The patient underwent a laparoscopic left hemicolectomy with an end colostomy and was started on an adjuvant chemotherapy regimen with no significant side effects.

Colorectal carcinoma can be associated with local or systemic abscess formation. When cultures from an abscess show enteric pathogens, it is essential to look to gastrointestinal or genitourinary tracts for the source of infection. Although rare, the diagnosis of pyomyositis should warrant further investigations to unmask the possible underlying cause.