Autoimmune-Associated Pulmonary Inflammatory Myofibroblastic Tumour: A Diagnostic and Therapeutic Challenge.

Pulmonary inflammatory myofibroblastic tumour (IMT) is a rare mesenchymal neoplasm with variable biological behaviour, ranging from benign inflammatory lesions to locally aggressive tumours. Its association with autoimmune phenomena remains unclear. We report a woman in her twenties with a prior diagnosis of lung IMT who re-presented with chronic respiratory symptoms, systemic features and radiological progression. Repeat evaluation revealed bilateral bronchocentric consolidation, positive antinuclear antibodies and histopathological findings consistent with fibro-inflammatory disease, without ALK expression or significant IgG4 infiltration. Concomitant erythema nodosum supported an autoimmune process. Repeat biopsy did not fully reproduce the original IMT morphology, and follow-up remains limited. She had significant clinical, functional and radiological improvement following immunosuppressive therapy. This case emphasizes the diagnostic complexity of lung masses in young patients and emphasizes the importance of considering autoimmune-associated IMT as a potentially reversible condition.