TEMPI Syndrome: Erythrocytosis in Plasma Cell Dyscrasia.

TEMPI (telangiectasias, erythrocytosis with elevated erythropoietin, monoclonal gammopathy, perinephric fluid collections, intrapulmonary shunting) syndrome is a newly described clinical entity that is generally considered a plasma cell dyscrasia with multiple system involvement. The etiology and pathophysiology of this condition remains elusive. Nevertheless, clonal plasma cells and monoclonal protein appear to be major contributors. The early diagnosis of TEMPI syndrome is essential because therapies targeting the underlying plasma cells can lead to a dramatic response. Bortezomib-based chemotherapy, daratumumab monotherapy, and autologous hematopoietic stem cell transplantation can result in reversal of most manifestations. Nevertheless, the diagnosis of TEMPI syndrome remains a substantial challenge owing to its rarity and the complexity of clinical presentations. TEMPI syndrome is often misdiagnosed as other causes of erythrocytosis, resulting in a delayed diagnosis and further clinical deterioration. The aim of the present review was to present the clinical and biologic features of TEMPI syndrome, highlighting the differential diagnosis and outlining the present understanding of its pathophysiology and treatment.