A case of primary psoas abscess presenting as buttock abscess

Abstract

Buttock abscess is a rare clinical manifestation from unusual extrapelvic extension of psoas abscess. A 48-year-old woman presented with painful swelling of the buttock with a sense of local heat. Magnetic resonance imaging revealed a large subfascial abscess over the glutei muscles and was traced into the intraabdominal cavity over the iliac wing to the psoas muscle. Both the psoas abscess and the buttock abscess were evacuated via separate approaches. Empirical antibiotic therapy was delivered for 3 weeks. After 6 months, no evidence of recurrence was found. Psoas abscess could be included in the differential diagnosis of buttock abscess.

Fig. 1

Axial magnetic resonance images show the extent of the abscess pocket. The manifest painful swelling of the buttock is due to subfascial pus collection (a), and the purulent fluid is connected to the intra-abdominal retroperitoneal and psoas abscess (b)

Fig. 2

The apparent buttock abscess was eliminated by direct approach over the lesion below the iliac wing, and the psoas and retroperitoneal abscess was eradicated by anterolateral retroperitoneal approach above the iliac wing. The closed suction drain was inserted into the retroperitoneum through the communicating channel between the buttock and the psoas lesions

Fig. 3

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)