Background: Pyomyositis is a rare, subacute, deep pyogenic infection of the muscle tissue. This disease has been previously described in patients that were immunocompromised due to a hematological malignancy.
Case presentation: A 68-year-old man with a history of chronic myeloid leukemia was treated with imatinib. He was diagnosed with ascending colon cancer and underwent curative surgery. His postoperative course was uneventful, and he was healthy at 6 months after surgery, allowing for reinitiation of imatinib therapy. After the reinitiation of therapy, a computed tomography (CT) scan revealed a mass shadow in the right iliopsoas muscle. This lesion was clinically diagnosed as recurrent colon cancer with an abscess, which was resected surgically. A pathological examination uncovered both edema and inflammation. Two months after the second surgery, imatinib therapy was reinitiated; however, he again developed painful swelling and erythema in his right thigh. A CT scan revealed a similar shadow as described previously. He was then diagnosed with pyomyositis; he underwent incisional drainage and was administered linezolid. Following the treatment for pyomyositis, there was no cancer recurrence or evidence of any recurrent pyomyositis.
Conclusions: Findings from this case suggest that both undergoing surgery and receiving imatinib therapy may modulate an individual's immune response, whereby the surgical site becomes more prone to infection and may predispose an individual to pyomyositis. The case report is followed by a discussion of the literature regarding this disease, including potential risk factors and the underlying pathogenesis.
Keywords: Imatinib; Pyomyositis; Surgical site.