Fig. 3
From: A case of primary psoas abscess presenting as buttock abscess
Spread of psoas abscess. Usual propagation of the abscess in the psoas along the insertion of the muscle into the lesser trochanter of the femur, then the medial side of the thigh, and even downward to the calf (A). Unique blowout of the psoas abscess in this case. The abscess expanded into the retroperitoneum, outside of the psoas muscle substance, and then reached the buttock through the posterior abdominal wall over the iliac crest (B). Psoas abscess may result in piriformis and gluteal abscess (C)