Case Presentation: A 63-year-old male with a past medical history of type 2 diabetes mellitus, paroxysmal atrial fibrillation, ESRD on HD, and acute myeloblastic leukemia (AML) (diagnosed in 2015) in remission s/p allogeneic MRD PBSCT (4/16) was admitted for generalized weakness and confusion. His hospitalization was complicated by worsening pancytopenia (Hgb 7.8 g/dL, WBC 3.2 k, ANC 1.31k, and plt 57k) with vitamin B12 and folate levels within normal limits. Bone marrow biopsy showed normocellular marrow with trilineage hematopoiesis and scattered, small non-caseating granulomas. PET/CT showed markedly heterogeneous background FDG uptake throughout the chest, abdomen, and pelvis likely related to anasarca and acute on chronic illness and heterogeneous background bone marrow FDG uptake that can be related to chronic illness/anemia. Diagnostic labs showed negative Quantiferon, MPO ab, and c-ANCA, elevated serine protease 3 ab (29 AU/mL), elevated alk phos (405 U/L), negative ANA, low C3 (78 g/ml), slightly elevated vitamin D 1,25 (98.2 pg/mL), and normal GGT, PTH, and C4. The results were not indicative of AML recurrence but were consistent with sarcoidosis. The granulomas observed in the bone marrow were thought to be the likely cause of the patient’s pancytopenia. Repeat biopsy with aerobic/anaerobic, fungal, and mycobacteria cultures was recommended as the first sample was insufficient for culture and he was discharged on prednisone for presumed sarcoidosis with PJP prophylaxis. A few weeks later, the bone marrow culture was positive for Mycobacterium haemophilum and was determined to be the driving force for his pancytopenia. His prednisone was tapered, vitamin D was stopped, and he was started on azithromycin, ethambutol, and rifabutin treatment. Once the culture sensitivities were finalized the ethambutol was switched to ciprofloxacin. Additionally, the case was reviewed by the team at National Jewish, who concurred with the treatment approach.
Discussion: Sarcoidosis is characterized by the formation of non-caseating granulomas. It commonly affects the lungs and lymph nodes, with isolated bone marrow involvement being rare and typically part of a systemic presentation Given the patient’s history of AML, it was crucial to exclude AML recurrence, as other common causes of granulomatous inflammation can present similarly. Mycobacterium haemophilum primarily affects immunocompromised patients. This patient’s history of stem cell transplant, ongoing immunosuppressive therapy, and ESRD allowed the bacterium to thrive. Due to these factors, Mycobacterium haemophilum was able to infect and proliferate within the bone marrow. The infection’s confinement to the bone marrow highlights the critical need to identify and manage opportunistic infections in patients with compromised immune systems.
Conclusions: This patient’s condition was initially diagnosed as sarcoidosis by exclusion, however, a positive bone marrow culture with Mycobacterium haemophilum identified the new diagnosis. Patients with severe immunocompromise on ongoing treatment may require enhanced prophylaxis against opportunistic infections, including Mycobacterium species. Managing similar patients requires careful monitoring and the consideration of uncommon pathogens.