Pictorial review of role of nuclear medicine imaging of paraneoplastic syndromes

Learning Objectives 1. Learn the pathophysiologic basis of development of various paraneoplastic syndromes 2. Understand the role of imaging with specific reference to the role of nuclear medicine techniques

Paraneoplastic syndromes are defined as clinical syndromes characterized by non-metastatic systemic effects associated with a neoplastic process, resulting from damage to organs and tissues remote from the original site of malignancy or its metastases. The pathophysiologic mechanisms implicated include production of antibodies to the tumor cells by the body which may cross react with normal tissues and production of physiologically active substances like hormones, hormone precursors, a variety of enzymes and cytokines. However, majority of the paraneoplastic syndromes are idiopathic. The reported incidence of paraneoplastic syndromes in the literature ranges from 2-20%. A wide array of body systems are affected, patients presenting with signs and symptoms referable to neurologic, hematologic, musculoskeletal, cardiovascular, renal, gastrointestinal, endocrine, dermatologic and psychiatric systems. These syndromes can precede the cancer presentation by months or even years and even when the cancer develops, the size of the tumor can be small and be occult, thus undetectable by the conventional diagnostic tests and imaging. Nuclear medicine imaging and particularly, PET/CT imaging may be an adjunct to timely diagnosis of the occult malignancy which can impact management and prognosis. In this pictorial exhibit, we present a review of the paraneoplastic syndromes with respect to the role of nuclear medicine imaging.