Myeloid leukemia cutis in the setting of myelodysplastic syndrome: a crucial dermatological diagnosis.

Cutaneous involvement by myeloid leukemic cells is an unusual phenomenon. Clinical manifestations vary from erythematous papules to plum-colored plaques and nodules that may become purpuric and ulcerate. The definitive diagnosis of myeloid leukemia cutis requires the analysis of biopsy specimens using immunohistochemical staining to determine the expression of selective cell surface markers. We will review myeloid leukemia when first evident in the skin, particularly in the setting of myelodysplastic syndrome. The diagnosis of leukemia cutis in patients with myelodysplastic syndrome is indicative of concomitant or impending acute leukemic transformation. The early recognition and accurate identification of leukemic skin infiltrates in myelodysplastic patients is crucial, as this finding can have significant therapeutic and prognostic implications.

Erythema toxicum neonatorum revisited.

Erythema toxicum neonatorum (ETN) is a common neonatal dermatologic disorder that usually is evident within the first 48 hours of life. Characteristic lesions include erythema, wheals, papules, and pustules. This transient rash resolves spontaneously without sequelae over the course of a week. Histologically, ETN shows an abundance of eosinophils. Although it has been recognized and described for centuries, the etiology and pathogenesis of ETN remain unclear.