Clinical history: A 45 year old man presented with a one month history of asymptomatic left chest rubbery pink-grey papules. A punch biopsy was performed.
What is your diagnosis?
Discussion and answer
The skin punch biopsy sections show a normal epidermis with a narrow band of uninvolved collagen lying between the epidermis and dermis (Grenz zone). Within the dermis is a dense cellular infiltrate that extends into the subcutaneous fat. The infiltrate is composed of large atypical cells with one to several prominent nucleoli and moderate amounts of finely granular cytoplasm. Eosinophilic precursor cells with red cytoplasmic granules and a mixture of mature and immature myeloid cells are present. Small groups of mature neutrophils are also observed. The infiltrate extends along the dermal appendages and blood vessels. Mitoses are identified in the abnormal cell
The histological features are those of leukemia cutis. The presence of eosinophil precursor cells within the infiltrate and the appearance of the abnormal cells are indicative of a myelogenous origin. The patient had a known diagnosis of chronic myelogenous leukemia (CML).