Mycobacterium terrae Complex Associated Lymphadenitis: Negative AFB PCR

Abstract Introduction/Objective Nontuberculous mycobacteria included with the Mycobacterium terrae complex (MTC) include a ubiquitous, slow-growing collection of mycobacteria known for causing severe resistant skin, joint, and bone infections. There are limited reports of M. Arupensis, included under MTC, causing human infections despite environmental ubiquity. Low sequencing sensitivity for species such as M. Arupensis may result in negative preliminary PCR speciation thus influencing the negative predictive value of this method of organism detection. No prior case reports have described MTC infection presenting as subacute lymphadenitis. Methods/Case Report A 48 year old El Salvadorian male with known diagnosis of HIV presented with oral thrush and significant left-sided lymphadenopathy. He was initially diagnosed with HIV in El Salvador and on ART until immigrating to the US six months prior. HIV antigen and antibody was positive with positive reflex viral PCR. QuantiFERON-TB Gold resulted positive, but CXR was without evidence of pulmonary TB. TB1, TB2, and mitogen minus NIL were negative. He was referred for fine needle aspiration and core needle biopsy of the left cervical lymph node. AFB and AFB FITE stains were performed, but no definitive mycobacteria were identified. GMS was performed and negative for fungal elements. A final histological diagnosis of necrotizing granuloma was given and the tissue was sent for bacterial, AFB, and fungal DNA PCR; no organisms were detected. A sputum sample was obtained and cultured four months after initial presentation and was positive for acid fast bacilli: Mycobacterium terrae complex, most closely resembling Mycobacterium arupensis. The Fite and AFB stains were again reviewed, revealing one single acid fast bacilli organism identified on Fite stain in the necrotizing granuloma. Results (if a Case Study enter NA) N/A Conclusion The negative AFB DNA PCR result may have been a false negative result due to poor sensitivity or selectivity for M. arupensis. There are no former reported cases of M. Arupensis associated necrotizing granulomas in lymph node. This unusual MTC infection presenting as chronic unilateral lymphadenitis underscores the importance of broadening clinical laboratory AFB DNA PCR sensitivity especially in cases of suspected AFB or modified AFB associated necrotizing granulomas.