Paraneoplastic hypereosinophilia in a patient with peripheral T cell lymphoma, not otherwise specified

Under normal physiological conditions, the bone marrow (BM) will have between 1% and 6% eosinophils, translating into a peripheral count of 0.05 - 0.5 ×10⁹/L eosinophils in the blood smear. This process is coordinated by transcription factors with specific roles in differentiation and activation. Secondary eosinophilia may be a paraneoplastic syndrome, related to the presence of a subsequent malignancy, as presented in this case report. Such paraneoplastic manifestations should be addressed properly in order for the patient to receive the best treatment of choice. Even if eosinophilia was associated with B-cell malignancies before, this is a report associating this symptom to a peripheral T-cell lymphoma, not other specified, thus emphasizing the importance of a complex approach for the management of the oncological patient.