Acute Lumbar Pain Revealing a Rare Localization of a Primary Squamous Cell Carcinoma of the Psoas

Damages to the psoas muscle are most often of infectious origin; other causes are observed, notably neoplasia and metastasis, hematomas, which sometimes pose a problem of care, especially in tumor-related conditions. Here, we report a rare case of psoas abscess associated with left pyonephrosis, revealing a squamous cell carcinoma of the left psoas without other tumor sites, along with the diagnostic and therapeutic approach taken in this case. This case report will make clinicians think about psoas muscle lesions, especially tumor lesions, which require a well-defined therapeutic approach.