Acute Myeloid Leukemia Cutis | Dermatopathology

The patient has an established history of acute myeloid leukemia. In the past, the patient's leukemic infiltrate showed positivity for CD34, CD117, and CD123. The patient's skin biopsy shows a blastic leukemic infiltrate around vessels, nerves, and adnexal structures within the dermis, and as well there is a leukemic panniculitis. The phenotypic profile would appear to be consistent with what has been demonstrated in the patient's prior specimens. The neoplastic cells are highlighted by CD45, CD31, CD34, CD117, and CD123 without significant immunoreactivity for myeloperoxidase, lysozymes, CD4, and CD56. The findings would therefore suggest an acute myeloblastic phenotype without evidence of significant monoblastic/monocyte differentiation. Two stains were evaluated for evidence of a concurrent infection, namely the Gram and PAS stains, and they are both negative.

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Slide 1: 65 year old man with a history of AML presenting with a new tender nodule over the knee. The clinical differential included Sweet syndrome and infection.

Slide 2: The biopsy shows an extensive infiltrate within the dermis and subcutis. Within the dermis, it is a non-effacing conspicuous pattern of infiltration around nerves and blood vessels.

Slide 3: The infiltrate is that of blastic-appearing hematopoietic elements ranging fron 10-12 microns.

Slide 4: The neoplastic cells have minimal amounts of light gray cytoplasm. The nuclei are round to oval, whereby the cells have fairly inconspicuous, small, basophilic nucleoli. The chromatin is relatively evenly dispersed.

Slide 5: The malignant hematopoietic infiltrate is highlighted by CD45.

Slide 6: There is extensive staining of the malignant cell populace for CD31 and CD34 (not shown).

Slide 7: A subset of neoplastic cells stain for CD117, likely in the 20% realm.