# Bone marrow mastocytosis associated with primary cutaneous follicle center lymphoma: an unusual case report

## TL;DR

A patient with bone marrow mastocytosis later developed a rare skin lymphoma, suggesting two separate conditions rather than a linked hematologic neoplasm.

## Contribution

This case report highlights a rare association between bone marrow mastocytosis and primary cutaneous follicle center lymphoma.

## Key findings

- The patient had bone marrow mastocytosis with CD25-positive mast cells and KIT D816V mutation.
- Nine years later, she developed primary cutaneous follicle center lymphoma, confirmed by histology.
- Radiation therapy effectively treated the skin lesions, indicating separate origins for the two neoplasms.

## Abstract

In a subset of patients with systemic mastocytosis (SM), an associated hematologic neoplasm (AHN) is identified. Most AHN are myeloid neoplasms, whereas lymphoid neoplasms are uncommon. We report on a 70-year-old female patient with bone marrow mastocytosis (BMM) associated with primary cutaneous follicle center lymphoma (PCFCL). Initially, the patient had developed BMM at the age of 61 years. Since then, she suffered from recurrent anaphylaxis and vitiligo. A BM investigation revealed several compact aggregates of MC exhibiting CD25 and the KIT mutation D816V. The basal serum tryptase level ranged between 26.0 and 30.9 ng/ml. Nine years after the initial diagnosis of BMM, the patient developed cutaneous nodular reddish lesions on her scalp. Histologic examination excluded mastocytosis and revealed PCFCL. Radiation therapy resulted in regression of cutaneous lesions. This unusual case demonstrates that patients with BMM may develop a lymphoid neoplasm in extramedullary sites, including skin. However, both neoplasms were separable from each other by site and pathology, which would argue for two separate etiologies and against a classical AHN.

The online version contains supplementary material available at 10.1007/s00277-025-06588-4.