Final Diagnosis

Mycobacterial fasciitis and myositis

Patient Follow-up

The patient was isolated and started on rifampin, isoniazid, pyrazinamide, and ethambutol to cover mycobacterium tuberculosis (TB) infection. Approximately 1 week after the muscle biopsy, the patient developed right ankle and hip pain as well as cervical lymphadenopathy. CT scan of the neck showed necrotic internal jugular lymphadenopathy consistent with scrofula. CT of the chest, abdomen, and pelvis demonstrated multiple bibasilar pulmonary nodules, necrotic mesenteric lymph nodes, and fluid collections of the right iliacus and psoas muscles. The patient was subsequently found to have positive TB cultures in sputum, bone lesions, and cervical lymph nodes. She underwent drainage of multiple fluid collections. The patient’s 6-month hospital course was complicated by drug rash, immune reconstitution syndrome, failure to thrive, worsening renal function and isoniazid-induced hepatotoxicity. Throughout the prolonged hospital course, she never demonstrated respiratory symptoms. She eventually showed significant improvement with the TB therapy and was discharged home with a plan to complete eleven total months of TB therapy.

Discussion

It is well known that patients with systemic lupus erythematosus are at increased risk for TB and other opportunistic infections because of the immunosuppression these patients require. Multiple studies have demonstrated that serious infections and extra-pulmonary manifestations are more common in this patient population [1, 2]. While approximately 3% of patients with TB have musculoskeletal involvement, the incidence of the even more uncommon manifestation of myositis is unknown [3]. It has been speculated that skeletal muscle is highly resistant to tuberculosis infection, based on its low oxygen and high lactate levels, as well as the lack of reticulo-endothelial tissue [4, 5].

Of the rare cases of TB myositis in the literature, it has been most commonly described in immunosuppressed patients, including those with systemic lupus erythematosus, rheumatoid arthritis, and HIV infection [3–5]. In each of the described cases of TB myositis, the diagnosis was made with fluid culture, and patients presented similarly with ongoing fever, pain, and swelling. To our best knowledge, this is the first reported case of TB fasciitis and myositis with the initially diagnosis suspected by muscle biopsy findings.

Granulomatous myositis is a rare muscle pathology diagnosis. It can be seen in association with sarcoidosis, infections, Churg-Strauss Syndrome, Crohn disease, and anti-PD1 therapy, among others [6–11]. Granuloma consists of epithelioid cells, multinucleated giant cells, lymphocytes and other inflammatory cells. Necrotizing granulomatous inflammation shows necrotic tissue with granular and cheese-like cellular debris in the areas with granulomas. It is mostly seen in mycobacterial and fungal infections. The necrotizing granulomatous fasciitis and myositis seen in our case is caused by TB infection.

Our case illustrates that febrile focal myositis should raise a strong clinical suspicion for infectious myositis. Infection work up should be done on muscle biopsy specimens. TB can infect muscle, and should be considered especially in immunocompromised patients even without pulmonary symptoms.

Pearls