Paraspinal extramedullary hematopoiesis in hereditary spherocytosis with a concurrent follicular lymphoma: case report and review of the literature

Abstract

We report an unusual case of a 70-year-old male with history of hereditary spherocytosis (HS) and secondary paraspinal extramedullary hematopoiesis with a concurrent follicular lymphoma. The lesion presented as a thoracic paraspinal mass of 9 cm, extending longitudinally between T6 and T9 vertebral bodies. Incisional biopsy revealed that this mass included mature hematopoietic tissue compatible with extramedullary hematopoiesis (EMH). The tissue also presented an extensive and diffuse infiltration by an atypical lymphoid population composed predominantly by small cells. The immunohistochemical study revealed that the atypical lymphoid population had a germinal center phenotype, consistent with the diffuse variant of follicular lymphoma (FL). The simultaneous presence of both EMH and FL in the same lesion made the interpretation and the final diagnosis of this case difficult. The presence of EMH in this clinical context may eclipse the diagnosis of the underlying lymphoproliferative neoplasm. The close association between the tumor cells and extramedullary hematopoietic tissue in the absence of lymphadenopathies or other tissue involvement suggests a relationship of this tumor with the recently described primary FL of the bone marrow.

Fig. 1

PET scan imaging before and after four weeks of Rituximab. a PET/CT scan before immunotherapy. Note a large metabolically active paravertebral mass of soft tissues adjacent to thoracic vertebral bodies T6 to T9 (arrow). A lesion in inter-aorto-caval mass is not visible at this level. b PET scan after immunotherapy; partial uptake reduction of the main thoracic paravertebral mass (arrow) and the inter-aorto-caval lesion (arrowhead)

Fig. 2

The biopsy of the paravertebral mass showed aggregates of mature hematopoietic tissue, with erythroid islands and normal megakaryocytes consistent with EMH, (a) H&E 40x, (b) H&E 200x. In other areas the tissue was diffusely infiltrated by an atypical lymphoid population of small cells with few large centroblast-like cells, (c) H&E 100x, (d) H&E 400x. The cells are positive for (e) CD20, (f) BCL6 and (g) BCL2. h FISH shows an IGH@/BCL2 translocation in some cells (yellow arrows), (dual color dual fusion probe, x400)