Leukemia cutis presenting as localized cutaneous hyperpigmentation

The usual clinical presentations of leukemia cutis include solitary infiltrated erythematous or violaceous plaques or nodules and multiple localized or generalized papules. On the other hand, cutaneous hyperpigmentation is a frequent finding in patients with malignancies, most of the cases because of chemotherapy or other drugs that the patient is taking. We present a case of cutaneous hyperpigmentation as the presenting sign of leukemia cutis. A 61-year-old male presented with cutaneous hyperpigmentation, which had appeared during the last chemotherapy cycle for treatment for biphenotypic leukemia. Cutaneous lesions consisted of bluish to brownish irregular well-defined discoloration of the skin involving the upper part of the trunk and the temporal regions of the forehead. The patient was asymptomatic and the skin was not infiltrated at all. However, histopathologic study showed nodular infiltrates involving the full-thickness of the dermis and destroying pre-existing adnexa. This infiltrate was composed of atypical basophilic cells with large hyperchromatic nuclei and scant cytoplasm. Immunohistochemical studies showed intense immunoexpression for CD43, CD68, CD45RO and myeloperoxidase within these cells. A diagnosis of biphenotypic leukemia cutis was established. In our review of the literature we have not found any report of cutaneous hyperpigmentation as the presenting manifestation of leukemia cutis.