[Coexistence of mycosis fungoides and essential thrombocythemia with JAK2V617F]

The coexistence of myeloproliferative neoplasms (MPNs), specifically essential thrombocythemia and lymphoproliferative neoplasms, are a very rare finding with a frequency < 1%.

We present the case of a woman with diagnosis of mycosis fungoides early stage IB, of 5 months of evolution, she received systemic treatment based on methotrexate orally for 4 months; after this, she started with important thrombocythemia reaching up to 1 200 000/mm3 platelets and leukocytosis ranging from 10 000 - 13000/mL. A study protocol for chronic myeloproliferative disease was performed, reporting 90% cellular bone biopsy, erythroid myeloid ratio 5:1, 25 megakaryocytes per mm3, some with hyperlobed nuclei, and giant nuclei. Karyotype: 46XX. PCR without expression of BCR/ABL. JAK 2 positive. The diagnosis of essential thrombocythemia was concluded.

There are several hypotheses seeking to elucidate the etiopathogenesis of the coexistence of myeloproliferative and lymphoproliferative neoplasms, some claim that they are precursors of the same multipotential stem cell, while others support that they are the result of a coincidence. More molecular studies are required to elucidate this unknown.