Hodgkin lymphoma as a novel presentation of familial DICER1 syndrome.

UNLABELLED: DICER1 germline mutations are associated with an inherited cancer syndrome, most commonly presenting with pleuropulmonary blastoma (PPB), ovarian sex cord tumors, thyroid cysts/goitre, and cystic nephroma. We describe the occurrence of a Hodgkin lymphoma (HL) of the T cell phenotype in a family with DICER1 syndrome. The patient presented with PPB Type I and HL. Immunohistochemical staining of the Hodgkin and Reed-Sternberg cells revealed CD30, TGP, CD2, CD3, CD15, and IRF4 positivity and weekly positivity of PAX5. T cell receptor repertoire analysis suggested HL of T cell origin, which is in contrast to common B cell-derived HL. The mother had been diagnosed with thyroid cysts, one sister had died from a primitive neuroectodermal tumor, and a brother had died from PPB Type III. Two mutational events were revealed in all affected family members; a single bp deletion, c.5299delC, leading to a frameshift and premature stop in exon 24 and a heterozygous variant (c.4616C>T; p.Thr1539Met) located in exon 23 of the DICER1 gene. This variant is predicted to be benign by in silico analysis.
CONCLUSION: Future studies looking for DICER1 mutations in HL cases of the T cell phenotype will be important to confirm its association with constitutional DICER1 syndrome. WHAT IS KNOWN: • DICER1 germline mutations are associated with an inherited cancer syndrome, most commonly pleuropulmonary blastoma, ovarian sex cord tumors, thyroid cysts/goitre, and cystic nephroma. • Hodgkin lymphoma is one of the most frequent types of malignant lymphomas and typically arises sporadically. T cell-derived Hodgkin lymphomas are exceptionally rare. What is New: • DICER1 syndrome may have an even broader phenotypic spectrum and seems to be associated with rare forms of T cell Hodgkin lymphoma.