Tuberculous pyomyositis is a rare entity, with nonspecific presentation that often leads to a delay in diagnosis. It is caused by a small aerophilic bacillus organism and spreads by exhaled respiratory droplets from affected individuals. When tuberculous pyomyositis presents as the initial and only manifestation of the disease, there is a diagnostic dilemma. Even with readily available advanced imaging studies, there are no pathognomonic findings indicative of the disease. Early and accurate recognition is essential to avoid additional morbidity, mortality, and public health risk.
Tuberculous pyomyositis has been reported as an opportunistic infection in patients with immunosuppression. Modern manifestations have been unmasked following medical therapy for respiratory infections treated with quinolone antibiotics1. It may present as painful soft-tissue swelling with conditions such as ankylosing spondylitis2, rheumatoid arthritis3, and polymyositis4. There is an increased incidence in individuals who are being treated with corticosteroids and disease-modifying antirheumatic drugs (DMARDS)5, and, paradoxically, in individuals with human immunodeficiency virus (HIV)6 that is being brought into remission with medication therapy7. There is an increased incidence in people who may be immunocompromised or who have a number of medical comorbidities, including diabetes mellitus, congestive heart failure, renal failure, drug addiction, systemic lupus erythematosis, nephrotic syndrome, and renal transplant. To the best of our knowledge, much of the literature pertaining to these conditions has been published from areas where tuberculosis (TB) is endemic. However, the defined patient population at risk is not necessarily defined by the pulmonary TB population, but rather by a population that is common in most hospitals in the United States.
The reported outcomes of tuberculous pyomyositis have varied widely, from complete disease remission to death. Early accurate diagnostic consideration is important in optimizing outcomes. With this report, we hope to raise ongoing awareness and improve public safety and patient care. The patient was informed that data concerning his case would be submitted for publication, and he provided consent.
A forty-year-old native Laotian man presented to our institution with symptoms of right hip and leg pain of seven months’ duration. He reported increasing pain with walking. He denied any injuries or having any medical comorbidities. He had no respiratory or constitutional symptoms. He reported chronic low back pain, vague abdominal aches, and diarrhea of three months’ duration. He was on disability because of anxiety and depression. He had been treated by a family physician with lorazepam and ibuprofen.
Physical examination revealed normal upright posture, the absence of spinal tenderness or spasm, and a functional unassisted gait. There was a large fluctuant mass involving the right buttock and lateral part of the thigh and hip. The overlying skin was intact. There was generalized tenderness in the involved area.
Laboratory studies revealed an elevated white blood-cell count of 11.4 mm3, a hemoglobin level of 9.2 g/dL, and a sodium level of 129 mmol/L. The results of the liver function tests were nonspecific, and the erythrocyte sedimentation rate was 115 mm/h.
Magnetic resonance imaging (MRI) of the right hip (Fig. 1) revealed a large collection of air and fluid overlying the greater trochanter and lateral aspect of the pelvis between the gluteus muscles. There was an associated complex fistula that extended medially to the sciatic notch. One component extended to the perirectal space, and the other extended into the space medial to the obturator internus muscle. There was also a component of the process that extended through the sciatic notch to involve the right half of the sacrum, a portion of the left half of the sacrum, a portion of the right ilium, and possibly the L5 segment.
The patient underwent debridement and biopsy of the fluctuant mass, the sacroiliac joint, and sacrum. At the initial debridement, nonspecific serous fluid and inflammatory soft tissue of the thigh, buttock, and osseous sacrum were noted. Duplicate specimens of the fluid, bone, and muscle were obtained. The acid-fast bacillus (AFB) smear was uniformly negative, but on postoperative day four, two of the soft-tissue TB cultures were positive. These cultures are routinely incubated for thirty days if negative cultures persist. Histological studies revealed acute and chronic inflammation, but no specific caseating granulomas.
The postoperative regimen included local wound care as well as several medications: isoniazid (300 mg daily), vitamin B6 (50 mg daily), rifampin (600 mg daily), ethambutol (1200 mg daily), and pyrazinamide (1500 mg daily).
Daily follow-up, including medication administration and daily wound care, was carried out by the Department of Health Directly Observed Therapy (DOT) program. The patient returned for monthly examinations by the treating orthopaedic surgeon, who monitored steady, sustained improvements in the clinical appearance of the wound, a decrease in the pain level, and a robust weight gain. At the final follow-up, he had completed an eighteen-month course of antituberculosis therapy, had no stated symptoms, had normal unassisted gait, and had motion and hip strength that was symmetric with the opposite side. A follow-up MRI of the right hip and pelvis revealed that the fistulas had resolved and that the previous bone abscess and muscular lesions had improved.
Tuberculous pyomyositis, when present in isolation, is a rare infection of skeletal muscle, which may be fatal and pose public health risks. In areas where TB is endemic, especially when there are known risk factors, there is an appreciation for extrapulmonary, extraskeletal disease. In regions where TB is uncommon, TB is not often considered as the causative agent in an isolated, painful, swollen soft-tissue mass. This can lead to a delay in diagnosis, which can be avoided by diagnostic consideration of TB and a request for an AFB smear and TB culture at the time of biopsy of a fluctuant soft-tissue mass8.
Our case of tuberculous pyomyositis occurred in a nonendemic area. The patient had no known TB involvement, had no known risk factors, had no associated symptoms (e.g., fever, sweats, or suggestive constitutional symptoms), and had no history of close family contacts with TB or recent exposure to TB. The radiographic findings were interpreted descriptively, indicating that the appearance was not specific; the findings became more specific only after the results of the culture were identified and the diagnosis was established.
When our patient initially presented for orthopaedic evaluation, he had been managed with ibuprofen for seven months in spite of massive swelling, fluctuance, and deformity. Once the workup was complete, it became clear that he had positive systemic findings and that there was some osseous involvement. The greatest “risk factor” was that he was a recent immigrant from Laos, an endemic area for TB. The diagnosis of Mycobacterium tuberculosis was confirmed by traditional culture and DNA probe.
There is reason to believe that the incidence of tuberculous pyomyositis may increase substantially. There is increased survivorship in individuals with the defined risk factors of congestive heart failure, systemic lupus erythematosus, diabetes mellitus, acquired immune deficiency syndrome, and chronic steroid use. There has been an increased use of DMARDS, which have specific known risks for allowing TB expression. Paradoxically, with effective HIV treatment, immune function may allow for TB expression, the so-called immune reconstitution inflammatory syndrome (IRIS). In addition, worldwide travel brings visitors from endemic areas. Another possible contributing factor is more efficient home and work heating systems, which include closed-circuit air handlers that can circulate airborne disease.
Patients with painful swollen extremities often present to the orthopaedic surgeon. If lesions do not seem familiar, TB should be considered as a diagnosis, and all biopsy material should be sent for culture. Cultures should include a specific request for an AFB smear and TB screening test. Tuberculous pyomyositis should be suspected even in the absence of known risk factors. In the presence of risk factors, it should be considered even if prior workups were negative.
Note: The author would like to acknowledge the assistance of David Schlossberg, MD, FACP, in preparing this manuscript.