Cutaneous non-tuberculous mycobacteria infection: a case report and literature review

Fialho, M. Pinto; Carvalho, M. M.; Catarino, A. M.; Casanova, S. R.; Sampaio, R.

http://hdl.handle.net/10400.21/21678

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Abstract(s)

Background & objectives: Non-tuberculous mycobacteria (NTM) are often overlooked as opportunistic agents causing cutaneous infections. While histological findings may resemble cutaneous tuberculosis, treatment and clinical management differ significantly. We present a case of NTM skin infection and a literature review. Methods: A 62-year-old female with autoimmune hepatitis, on immunosuppression, received a corticosteroid injection in the elbow joint. Six months later, she presented with a skin nodule at the injection site, histologically diagnosed as cutaneous tuberculosis. Despite being asymptomatic and lacking epidemiological context or chest X-ray abnormalities, a second adjacent skin nodule developed and was subsequently biopsied. Results: The skin biopsies showed poorly formed epithelioid nonnecrotizing granulomas with neutrophilic microabscesses (suppurative granulomas) and Langhans-type multinucleated giant cells in the reticular dermis and subcutaneous tissue. Gram and Grocott stains were negative, and acid-alcohol-resistant bacilli were observed using the Ziehl-Neelsen stain. As suggested by Song et al., we identified small vessel proliferation with sparse fibroblasts within the lesions. The histological examinations were consistent with NTM skin infection and confirmed by polymerase chain reaction (PCR). Conclusion: The case underscores the diagnostic challenge posed by NTM infections, often mimicking cutaneous tuberculosis. These histopathological findings should help pathologists decide when to suspect an NTM infection, avoiding a delay in diagnosis and a tuberculosis label that could lead to overtest and unnecessary treatments.

Keywords

Non-tuberculosis mycobacteria Skin infection Case report Literature review

URI

http://hdl.handle.net/10400.21/21678

Citation

Fialho MP, Carvalho MM, Catarino AM, Casanova SR, Sampaio R. Cutaneous non-tuberculous mycobacteria infection: a case report and literature review. In: 36th European Congress of Pathology, Convention Centre Dublin (Ireland), September 7-11, 2024. Virchows Arch. 2024;485(Suppl 1):S224-5.