Hodgkin's lymphoma is a rare form of clonal haematological non-mast cell disease in systemic mastocytosis

Abstract

Background: The association of systemic mastocytosis (SM) with a non-mast cell haematological neoplasm represents a specific subtype of mastocytosis termed systemic mastocytosis with associated haematological non-mast cell disease (SM-AHNMD). The overwhelming majority of the associated neoplasms are of myeloid origin, while lymphoid neoplasms associated with SM have been reported rarely. Association of SM with Hodgkin's lymphoma (HL) is exceedingly rare; so far, only two cases of HL as associated hematological non-mast cell disease in systemic mastocytosis have been published in the recent English literature. Case: We present a case of a 37-year-old otherwise healthy male who was referred to our institution because of a one-month lasting dysphagia of both hard and liquid food. Physical examination showed tumour in the left jugular area measuring 2cm in the largest diameter while computer tomography of the thorax revealed a 5.2cm large, hypodense, soft tissue tumour between the trachea and left arteria carotis communis. On the basis of FNAB findings, the diagnosis of a "neutrophil-rich" Hodgkin's lymphoma was established. Excisional biopsy of mediastinal tumor showed lymphoid neoplasm with morphology and immunophenotype consistent with nodular sclerosis classical Hodgkin's lymphoma (NScHL). Bone marrow trephine biopsy and the MGG-stained smear of the bone marrow aspirate performed for lymphoma staging revealed an existence of systemic mastocytosis which was unexpected and incidental finding. Mast cells were highlighted by CD117 and tryptase immunostainings while CD25 positivity of mast cells was consistent with their neoplastic phenotype. There were no HL infiltrates present in the bone marrow. Conclusion: We report a very rare combination of systemic mastocytosis with Hodgkin's lymphoma as associated clonal haematological non-mast cell lineage disease. Systemic mastocytosis was an unexpected finding. The diagnosis of SM in bone marrow in our case was straight-forward, but it can be difficult in the case of reactive lymphoid aggregates or a difficult distinction between SM and HL infiltration. In particular, distinction can be challenging from the immunohistochemical point of view in the case of high-grade mast cell disease which can be CD30 positive.