Paraneoplastic syndromes are rare diseases caused by malignancies through means other than mass effect or metastasis. Paraneoplastic phenomena can be the first sign of cancer and can be fatal. Paraneoplastic rheumatic syndromes can occur with hematologic cancers, lymphoproliferative disease, and solid tumors. Diseases that feature an advanced age at onset, significant constitutional upset, inadequate response to treatment, and otherwise atypical characteristics should increase the index of suspicion for a paraneoplastic syndrome.