Granulomatous Dermatitis Heralding Myelodisplastic/Myeloproliferative Neoplasms. Neoplastic or Reactive Cells? A...

Skin manifestations in the context of underlying hematological malignancies are well known and not an infrequent clinical finding. They can represent specific neoplastic infiltrates or be considered as reactive. In the latter group, where granulomatous dermatitis is included, controversy has emerged recently. According to newly reported data, the histiocytes comprising these granulomata can carry the same molecular alterations found in the primary process. Moreover, the skin manifestations in these patients are sometimes the initial clue for the diagnosis of the underlying malignancy. We present here 2 cases with granulomatous skin infiltrates preceding the diagnosis of myelodysplastic/myeloproliferative neoplasms. In one of them, the same IDH2 mutation was detected in granulomatous lesions on the skin and in the bone marrow. This was performed by pyrosequencing instead of next-generation sequencing, with improved cost-effectiveness.