C68-29 A Challenging Diagnosis of Non-Tuberculous Mycobacterial Infection and Sarcoidosis

Abstract Introduction Sarcoidosis is a multisystem disease of uncertain etiology, suspected to have environmental and genetic contributors. It often presents with constitutional symptoms such as fatigue, weight loss, and fever. Diagnosis is based on clinical and radiographic findings, exclusion of alternative diagnoses, and histopathologic evidence of non-caseating granulomas. This case highlights the diagnostic complexity of concurrent sarcoidosis and non-tuberculous mycobacterial (NTM) infection. Presentation A female in her early 50s with a history of right breast LCIS (post-lumpectomy, completed 5 years of tamoxifen), CKD stage 3a, chronic leukopenia, dyspepsia, peripheral neuropathy, and prediabetes was referred for routine breast imaging. A left axillary breast mass (BIRADS 4) was found. Needle and excisional biopsies showed necrotizing granulomatous inflammation, AFBand GMS stains were negative. Differential included TB, NTM, cat-scratch disease, sarcoidosis, vasculitis, and malignancy.Initial workup revealed positive sputum AFB cultures for MAI and elevated ACE. RIPE therapy was initiated but discontinued due to severe side effects and negative tuberculosis PCR. The patient was transitioned to MAI-directed therapy (Rifampin, Azithromycin, Ethambutol); however, Rifampin was discontinued due to persistent fevers. Inflammatory markers (CRP, ESR) were elevated, and active malignancy and MTB were ruled out. Imaging identified a new enlarged inguinal lymph node, which on biopsy revealed non-caseating granulomas. Despite continued MAI treatment, symptoms persisted, including weight loss, abdominal pain, and early satiety. Given the persistent symptoms, a prednisone trial was initiated, leading to significant symptomatic improvement. Following steroid initiation, the patient remained on MAI therapy with Rifabutin (due to Rifampin intolerance), Azithromycin, and Ethambutol, along with PCP prophylaxis (Bactrim). However, her rapid improvement with steroids suggests sarcoidosis was the primary culprit behind her symptomatology. Discussion Investigations into the relationship between Mycobacterium and Sarcoidosis, two histopathological similar disease entities, have been ongoing for over a century. Prior literature reveals both molecular and microbiologic evidence that there exists a correlation between mycobacterial infection and Sarcoidosis, however, no causative link has yet been identified. Hypotheses for their coexistence include T-cell immune-triggered responses, genetic susceptibility, and delayed bacterial clearance. Although most of the research has focused on the association between MTB and Sarcoidosis, less consideration has been given to NTM. Our case adds to the literature correlating Sarcoidosis with NTM. Conclusion This case underscores the diagnostic complexity of sarcoidosis in the setting of NTM infection. Distinguishing between the two is crucial, as coexistence may suggest a link between mycobacterial antigens and sarcoidosis. Accurate diagnosis is key to effective management. This abstract is funded by: None