Pyoderma gangrenosum can be the first cutaneous manifestation of paraneoplastic syndromes. Among the associated diseases include hematological malignancies. These disorders may have atypical clinical characteristics, with the association of Myelodysplastic Neoplasm (MDS) with the bullous form being the most described and its appearance associated with poor prognosis.

To report a case of skin lesion as a first manifestation of MDS.

A 68-year-old woman started with fatigue and pain in the legs, evolving with the appearance of plaques with haemorrhagic blisters in the left calf and the presence of cytopenia was identified in laboratory tests (Haemoglobin 6.7 g/dL, leukocytes 2.300/mm3, and neutrophils 552/mm3, and platelets 95.000/mm3). Patient sought medical assistance and started a clinical investigation. During follow-up serologies were performed with all negative results. Myelogram was performed and immunophenotyping showed the presence of 18.7% of myeloid lineage blasts with aberrant CD7 marking. The patient was diagnosed with MDS, the treatment with dapsone was started, but the patient died a few months after diagnosis. Discussion: The diagnosis of pyoderma gangrenous is one of exclusion and other causes of ulcer disease should be investigated. Myelodysplastic Neoplasm should always be considered in patients with pyoderma gangrenosum accompanied by some mono, bi or pancytopenia and may appear at the same time with the hematological disease or, in its evolution, as a marker of malignant transformation.

Myelodysplastic neoplasm should always be considered in patients with pyoderma gangrenosum accompanied by some cytopenia.