Low Back Pain: A Case of Malakoplakia

A 74-year-old man presented to his primary care provider with a 1-month history of new-onset low back pain. The patient was diagnosed with acute lumbago and was treated with muscle relaxants, nonsteroidal anti-inflammatory drugs (NSAIDs), and osteopathic manipulative treatment.

At his follow-up evaluation, the patient's symptoms did not improve and was also diagnosed with a urinary tract infection. He was treated with trimethoprim-sulfamethoxazole, and imaging studies were ordered.

A computed tomography (CT) scan of the abdomen (Figure) and spine revealed a necrotic psoas mass arising from his right kidney, 10.1 × 3.5 × 8.0 cm. Upon further questioning, the patient admitted to a 30-lb weight loss over the course of several months. The patient was subsequently admitted to the hospital for concerns of an underlying neoplastic process.

His vital signs upon admission were stable, and physical examination revealed a 10-cm fluctuating right flank mass. His medical history was significant for myasthenia gravis, hypertension, hyperlipidemia, and chronic steroid use. 

Laboratory Results. Pertinent laboratory findings included leukocytosis of 20,000 per mm3 and creatinine of 1.28 g/mol. Further, CT chest imaging showed a new 2-cm well-circumscribed right upper lobe lung nodule. The patient underwent a percutaneous drainage of the right renal abscess, a CT-guided lung biopsy, and a core renal biopsy.

The abscess culture grew Escherichia coli, and the patient was treated with intravenous piperacillin-tazobactam. The patient’s pulmonary nodule biopsy was nonmalignant and consistent with scar tissue formation.

The renal biopsy led to an initial diagnosis of oncocytoma, a benign renal neoplasm of perirenal tissue. However, the diagnosis of oncocytoma was inconsistent with the aggressive nature of the patient’s clinical condition, and the patient underwent a laparoscopic radical right nephrectomy. During the procedure, the right kidney and significant residual tissue was removed. The results of this concurrent renal biopsy revealed the final diagnosis of renal malakoplakia, a rare inflammatory condition. The patient improved and was discharged on levofloxacin for 16 days.

 

DISCUSSION >> 

A 74-year-old man presented to his primary care provider with a 1-month history of new-onset low back pain. The patient was diagnosed with acute lumbago and was treated with muscle relaxants, nonsteroidal anti-inflammatory drugs (NSAIDs), and osteopathic manipulative treatment.

At his follow-up evaluation, the patient's symptoms did not improve and was also diagnosed with a urinary tract infection. He was treated with trimethoprim-sulfamethoxazole, and imaging studies were ordered.

A computed tomography (CT) scan of the abdomen (Figure) and spine revealed a necrotic psoas mass arising from his right kidney, 10.1 × 3.5 × 8.0 cm. Upon further questioning, the patient admitted to a 30-lb weight loss over the course of several months. The patient was subsequently admitted to the hospital for concerns of an underlying neoplastic process.

His vital signs upon admission were stable, and physical examination revealed a 10-cm fluctuating right flank mass. His medical history was significant for myasthenia gravis, hypertension, hyperlipidemia, and chronic steroid use. 

Laboratory Results. Pertinent laboratory findings included leukocytosis of 20,000 per mm3 and creatinine of 1.28 g/mol. Further, CT chest imaging showed a new 2-cm well-circumscribed right upper lobe lung nodule. The patient underwent a percutaneous drainage of the right renal abscess, a CT-guided lung biopsy, and a core renal biopsy.

The abscess culture grew Escherichia coli, and the patient was treated with intravenous piperacillin-tazobactam. The patient’s pulmonary nodule biopsy was nonmalignant and consistent with scar tissue formation.

The renal biopsy led to an initial diagnosis of oncocytoma, a benign renal neoplasm of perirenal tissue. However, the diagnosis of oncocytoma was inconsistent with the aggressive nature of the patient’s clinical condition, and the patient underwent a laparoscopic radical right nephrectomy. During the procedure, the right kidney and significant residual tissue was removed. The results of this concurrent renal biopsy revealed the final diagnosis of renal malakoplakia, a rare inflammatory condition. The patient improved and was discharged on levofloxacin for 16 days.

 

DISCUSSION >>