Q1: What is the differential diagnosis?

The differential diagnosis is (1) a haemorrhagic diathesis (haemophilia) with haematoma formation in psoas and gluteal muscles and (2) a bilateral psoas abscesses.

Though haemarthrosis, spontaneous/traumatic, is the most common and characteristic manifestation of haemophilia, spontaneous bleed into fascial planes and muscles of the abdomen causing retroperitoneal haematoma is also relatively common in haemophilia A.1Bleed into or around the iliopsoas muscle produces pain of progressive and increasing intensity and tenderness. When it occurs on the right side, it may very closely mimic acute appendicitis, appendicular mass or abscess, pelvic abscess, psoas cold abscess, and in females tubo-ovarian mass.2-4 Fluid dense lesions in the gluteal muscles in addition to those of the psoas muscle region favour the presumptive diagnosis of haemophilia.

Tubercular psoas abscess can be a sensible differential diagnosis for a mass lesion in the iliolumbar region. As atypicality is the rule with tuberculosis, cold abscess of psoas also is a high diagnostic possibility, despite bilateral occurrence being rare. It usually presents as pain in the abdomen, hip, flank, spine with limping, psoas sign, and a fluctuant mass both above and below the inguinal ligament, with a gibbus deformity in the spine. In the case illustrated, trauma was probably incidental, misleading the clinician towards a diagnosis of traumatic psoas haematoma.

Q2: What other investigations would you consider?

Other investigations to be considered are complete coagulation profile and radiography of the thoracolumbar spine.

Q3: What features are atypical in the case illustrated?

Atypical features in the case illustrated are:

• Lack of local symptoms such as backache and gibbus deformity.

• Absence of systemic symptoms of fever and weight loss.

• Lack of psoas sign and flexion deformity of the hip.

• Bilateral occurrence of psoas abscess. • Fluid dense lesions in the gluteal muscles in a psoas abscess are very unusual.

• Trauma to the abdomen—a coincidental history may mislead the clinician to a haemorrhagic diathesis.

Discussion

This case illustrates an unusual presentation of caries spine with bilateral psoas abscess extending up to the gluteal region. In the context of steadily increasing abdominal discomfort after a blunt injury and mass lesions in the psoas and gluteal muscles, one should suspect a coagulation disorder such as haemophilia. But coagulopathy was ruled out as the clotting time, bleeding time, prothrombin time, activated partial thromboplastin time, and clotting factors 8 and 9 were normal. Radiography of the thoracolumbar spine showed reduced disc space between the L1 and L2 spine with osteolytic areas and sclerosis in the L1 and L2 vertebrae (see figs 1 and 2). A closed vertebral biopsy was done. Histopathological examination revealed a granuloma composed of epithelioid cells, multinucleated Langhans type giant cells, fibroblasts, and lymphocytes around a central area of caseous necrosis, suggestive of tubercular osteomyelitis. Ultrasonography guided aspiration of the mass drained around 900 ml of pus from the right side and 500 ml from the left side. The pus was abundant with acid fast bacilli, but was sterile on culture.

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Figure 1

Radiograph of lumbar spine (anteroposterior view). Note narrowing of the L1–L2 space (arrows).

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Figure 2

Radiograph of lumbar spine (lateral view) showing osteolytic area in the body of L1 vertebra (arrows). Note narrowing of the L1–L2 space.

Final diagnosis

Tubercular osteomyelitis of lumbar spine with bilateral tubercular psoas abscesses.