Paraneoplastic inflammatory myositis (PIM) comprises a rare subset of paraneoplastic syndromes (PNS) that arise from immune-mediated mechanisms rather than direct metastatic infiltration of skeletal muscle. While a strong association between malignancy and inflammatory myopathy (IM) is well-established, diagnosis remains challenging due to non-specific presentations that mimic primary autoimmune, metabolic, or infectious conditions. In many instances, muscular symptoms precede or coincide with the cancer diagnosis, necessitating a high degree of clinical suspicion. This case series highlights the clinical presentations of diverse neoplasms, including breast, ileal, thyroid, atypical carcinoid, and prostate carcinomas, where myopathy served as a critical clinical clue to an underlying occult malignancy. 18 F-FDG PET/CT plays a pivotal role in these cases by detecting occult primary tumours or disease progression with higher sensitivity and specificity than conventional imaging, while simultaneously identifying metabolic muscle involvement. A comprehensive approach integrating multimodality imaging, serological testing, and focused oncologic evaluation is essential for timely recognition and accurate staging. Ultimately, prompt treatment of the underlying malignancy often leads to significant resolution of paraneoplastic muscle symptoms, reinforcing the importance of an integrated diagnostic and therapeutic strategy.
Kumar et al. (Tue,) studied this question.