TEMPI syndrome is a rare multisystem paraneoplastic constellation of findings associated with an underlying plasma cell dyscrasia. First described in 2011, TEMPI is an acronym for telangiectasias, erythrocytosis (with elevated erythropoietin), monoclonal gammopathy, perinephric fluid accumulation, and intrapulmonary shunting.

At the time of writing, 15 cases have been reported. All patients had onset between the ages of 35 and 65, with a median age of 49 years. Onset is insidious.

Telangiectasias are seen in a majority of patients and are usually located on the face, trunk, and arms. They are thought to be related to the underlying hypoxia present. Erythrocytosis and elevated erythropoietin levels are characteristic.

Erythrocytosis appears to precede hypoxemia. A proposed explanation is that of renal micro-injury related to monoclonal immunoglobulin (Ig) deposition and subsequent erythropoietin (EPO) secretion.

Monoclonal gammopathy is usually of the IgG-kappa subtype, although IgG lambda and IgA lambda have rarely been reported. Peripheral plasma cell levels are usually less than 15%, and in all reported cases, bone marrow studies did not fulfill diagnostic criteria for plasma cell myeloma.

The etiology of perinephric fluid collections is not well understood; patients may present with abdominal fullness, flank tenderness, hypertension, or nausea. Overt renal dysfunction is uncommon. Imaging (abdominal ultrasound or CT) can reveal bilateral fluid collections surrounding the kidneys, and aspiration will yield a benign, mostly acellular fluid.

Intrapulmonary shunting has been noted in all cases of TEMPI syndrome to date, with hypoxia and oxygen saturation less than 90% on average. The hypoxia appears to be progressive, and some patients may present with dyspnea on exertion and clubbing, while other patients may present with a chronic oxygen need and use of assistive devices for ambulation.