# Unusual painful pelvic masses: Extramedullary hematopoiesis with extramedullary multiple myeloma

## TL;DR

This paper reports a rare case where two blood-related conditions coexist and appear as painful masses in the pelvis, making diagnosis difficult.

## Contribution

The paper highlights the rare coexistence of extramedullary hematopoiesis and extramedullary multiple myeloma in a clinical case.

## Key findings

- Extramedullary hematopoiesis and extramedullary multiple myeloma can coexist in the same pelvic mass.
- Normal blood cells may outnumber cancerous plasma cells, complicating diagnosis.
- CT-guided biopsy and immunohistochemistry are useful for identifying both conditions.

## Abstract

The coexistence of extramedullary hematopoiesis and extramedullary multiple myeloma can occur and present as painful pelvic masses. In such a case, normal hematopoietic cells may outnumber clonal plasma cells, posing a diagnostic challenge.

Computed tomography‐guided biopsy of the right iliac fossa mass showing extramedullary hematopoiesis with extramedullary multiple myeloma (A, B; yellow arrow: erythroid island; green arrow: myeloid cell; white arrow: megakaryocyte; black arrows: atypical plasma cells with prominent nucleoli; short black arrow: Dutcher body in an atypical plasma cell). CD61 (C) and CD138 (D) immunohistochemistry stains highlight megakaryocytes and plasma cells, respectively.