MPN-246: General Characteristics and Outcome of Renal Extramedullary Hematopoiesis in Patients with Myeloproliferative Neoplasms: A Literature Review

Abstract

Context: Kidneys are a rare but serious site for extramedullary hematopoiesis (EMH) with myeloproliferative neoplasms (MPNs). Objective: To review cases of EMH affecting the kidneys, focusing on demographics, clinical manifestations, treatment, and outcomes. Design and Setting: We reviewed the literature for studies, case series, and case reports that reported on renal EMH with a primary or background diagnosis of MPN from 1990 to 2020. Results: Forty-three patients (79% males) were retrieved. The mean age of the cohort was 65 years (range 49–87 years). Most of the cohort was white Caucasian (91%). The type of MPN was mostly MF, seen in 35 patients (81.4%), while PV was seen in 5 patients (11.6%), and ET and CML were seen in 2 patients (4.7%) and 1 (2.3%) patient, respectively. The most common renal manifestations were renal failure and nephrotic syndrome in 39.5% of the cases, followed by renal failure alone (37.2%) and nephrotic syndrome in 9.3%. Interestingly, a renal mass was found in 9%. The average time to EMH development from the time of diagnosis was 7.8 years (range 0–20 years). Four patients developed EMH post-transplant, 3 of them allogenic while one was autologous. The JAK mutation was reported in 7 patients, and CALR mutation in one patient. Patients were treated with different medications, including diuretics, anti-hypertensives (mainly ACE inhibitors), and steroids. However, for MPNs, 25% received HU, 14% received thalidomide or a thalidomide analog, while 16% received JAK inhibitors, such as ruxolitinib. The CML case was treated with imatinib. The average duration of follow-up was 19 months, with a 42.5% death rate by the end of follow-up. Kidney function improved in 31% of patients, with ruxolitinib administration correlating with improved kidney function and survival (6 out of 7 patients). Conclusions: An unexplained increase in renal function, proteinuria, or kidney mass in a setting of MPN should raise the suspicion of this diagnosis. There is currently no consensus or guidelines on the management of such cases. Ruxolitinib, with the limitations of small numbers treated, may offer some benefit; however, further studies and exploration of this drug and others in well-constructed prospective studies are needed.