A case series of malignancies: mimics of Rheumatological disorders

Background: Malignancy and Autoimmunity interplay is full of complexities. We here, describe few cases of malignancies presented as mimics of autoimmune disorders. A case of acute myeloid leukaemia had leukocytoclastic vasculitis, positive ANA, positive SS-A, and few clinical features of autoimmune disease and it mimicked UCTD. Second case of signet ring cell type of adenocarcinoma of G.I tract mimicked CTD as it had ANA positivity and ILD. Third case was epitheloid sarcoma which mimicked pyomyositis while fourth case was multiple myeloma presented with leukocytoclastic vasculitis, positive ANA, malar rash and active urinary sediments and it had mimicry of SLE. Malignancies can present as autoimmune diseases or they can mimic flare of Rheumatological diseases. Cancer can present as vasculitides, CTDs, myositis or arthritides. Sometimes, it is difficult to ascertain whether autoimmune disorders have caused cancers or malignancies have caused autoimmune disturbances. ANA can be positive in upto 27% cancer patients. There is clearly increased risk of cancers amongst patients of autoimmune diseases compared to general population. Malignancies including metastasis can also present with true paraneoplastic autoimmune disorders. They usually present later in the course of the disease but sometimes surprise internists with sudden appearance in early course of the disease. High index of suspicion is required to detect malignancies in autoimmune diseases as both have invariably similar presentations. PET scan and tissue diagnosis are amongst the major investigations to treat patients with spectrum of malignancy and autoimmunity.