Systemic Mastocytosis in Association with Small Lymphocytic Lymphoma

Abstract

BACKGROUND Systemic mastocytosis with an associated hematologic non-mast cell lineage disease is a rare entity, and the majority of systemic mastocytosis cases are associated with myeloid neoplasm. Lymphoproliferative disorders are less commonly associated with systemic mastocytosis and a few cases of systemic mastocytosis associated with chronic lymphocytic leukemia have been described in the literature. CASE REPORT We present a case of indolent systemic mastocytosis associated with small lymphocytic lymphoma. The bone marrow biopsy demonstrated mast cells in the form of clusters and perivascular distribution on immunohistochemistry for tryptase, CD2, and CD25 markers. In addition, 30% involvement by small lymphocytic lymphoma was discovered in the form of interstitial lymphoid aggregates composed of small lymphocytes. Flow cytometry showed B-cells positively stained for CD19, CD20, CD5, CD23, and kappa light chains, and the CD38 expression was <5%. CONCLUSIONS In systemic mastocytosis with an associated hematologic non-mast cell lineage disease, the combination of systemic mastocytosis associated with small lymphocytic lymphoma is rare and the management strategy follows the principle of treating the two entities individually as if they are not related. Clinical surveillance is indicated for indolent systemic mastocytosis and low-risk small lymphocytic lymphoma to monitor for disease progression.

Figure 1.

(A) Bone marrow crush preparation shows mast cell with surrounding maturing granulocytes (Wright stain ×1,000). (B) A degranulating mast cell as indicated by an arrow.

Figure 2.

Immunohistochemical stains show that the lymphoid infiltrate is composed of mainly B-cells (CD20+ A). There is increased interstitial population of mast cells with perivascular accentuation as highlighted by the tryptase stain (B).

Figure 3.

(A, B) Hematoxylin and eosin sections of clot show bone marrow with several intermediate sized interstitial lymphoid aggregates composed of small lymphocytes. (200×, 500×).