Multiple myeloma and its rare paraneoplastic manifestations simmering under the surface.

Paraneoplastic syndromes are complex clinical manifestations that occur because of the underlying malignancy in which the malignant cells produce hormones, cytokines, peptides or antibodies that causes symptoms and may affect multiple organ systems. These paraneoplastic conditions may be associated with different solid and hematological malignancies. Multiple Myeloma (MM) accounts for 10-15 % of hematological malignancies and 1-2 % of all malignancies. It is associated with some atypical clinical and laboratory paraneoplastic manifestations. Although there is a low incidence of these paraneoplastic, significant knowledge of these manifestations may assist in making a differential diagnosis in cases of doubt. The clinical presentation may vary and be evident even before or after the diagnosis of malignancy. These include vascular, neurological, dermatological, physiological, and other atypical conditions. Furthermore, these rare paraneoplastic manifestations need more valid, relevant scientific information, as most information about these conditions is derived from case reports. After the literature search, we have reported the paraneoplastic manifestations associated with multiple myeloma, published in the English literature, and the cognate management in this review article. To our knowledge, this is the first review article discussing various paraneoplastic manifestations of multiple myeloma.