Pyoderma gangrenosum associated with pseudo-Pelger-Huet anomaly in a patient with idiopathic myelofibrosis.

Pseudo-Pelger-Huët anomaly is a condition in which almost all the granulocytes are hyposegmented and/or hypogranulated. It is typically recognized in peripheral blood smears and represents a marker of several disorders, such as myeloproliferative diseases and myelodysplasia. The occurrence of the pseudo-Pelger-Huët anomaly in the cutaneous infiltrate of pyoderma gangrenosum is very rare. We describe the case of a 70-year-old man with idiopathic myelofibrosis who developed pyoderma gangrenosum. Histological examination showed an infiltrate consisting of granulocytic elements with features of dysmaturity and segmentation anomalies (hypo- and hypersegmented forms), suggestive of pseudo-Pelger-Huët anomaly. Methylprednisolone treatment resulted in progressive improvement of pyoderma gangrenosum.