An Unusual Case of Extramedullary Hematopoiesis in the Right Kidney

Abstract

Extramedullary hematopoiesis (EMH) is the formation of blood cells outside the bone marrow, typically occurring in response to chronic anemia or bone marrow dysfunction. While EMH is most commonly observed in the liver, spleen, and lymph nodes, its occurrence in the kidney is exceedingly rare. In this case report, we are presenting a case of a 49-year-old male diagnosed with polycythemia vera who had an incidental right renal mass, which was histo-pathologically proven as extramedullary hematopoiesis in the right kidney mimicking lymphoma. This case underscores the importance of considering EMH in the differential diagnosis of renal masses, especially in patients with a history of myeloproliferative disorders. Early recognition and appropriate management are crucial to avoid unnecessary interventions and manage the underlying hematological condition effectively. Accurate diagnosis through histopathological examination is crucial to avoid unnecessary surgical interventions.

Keywords: emh; extramedullary hematopoiesis; polycythemia vera; renal mass; renal tumour.

Figure 1. (A) Axial and (B) coronal reconstructed contrast-enhanced CT image in the arterial phase showing gross splenomegaly.

Figure 2. (A) Axial contrast-enhanced CT image showing numerous vascular structures adjacent to the portal vein, which enhance during the portal venous phase, suggestive of portal cavernoma. (B) Few nonenhancing hypodense-infarcted areas in the spleen.

Figure 3. Contrast-enhanced CT images in venous (A) and delayed phases (B) showing a well-defined, solid, mildly enhancing lesion measuring 5.8 × 5.7 × 4.9 cm occupying the right renal pelvis causing a splaying of the collecting system.

Figure 4. Histopathological image (10x) revealed cores of tissue showing extramedullary trilineage hematopoietic elements with full maturation (myeloid, erythroid, and megakaryocytic) admixed with mature adipose tissue and no atypical cells, consistent with EMH.