Leukemia Cutis Secondary to CLL

This very nice gentleman is a patient of mine who has been with me for well over a decade, and he presented about two weeks ago with a nodule on the scalp which was biopsied and found to be a squamous cell carcinoma.  Interestingly, though, my pathologist (she is very good!) noted sheets of lymphocytes around the lesion and asked me if, perchance, our patient had CLL.  The answer, of course, was yes, but it was well controlled.  Up til now, that is.

We scheduled him for surgery within two weeks, as we do all invasive SCCs, and when he came to the office for the surgery, he mentioned he had some swelling on his forehead for the last couple of days.  The plaques were slightly erythematous, firm to the touch and warm.  Well, the differential diagnosis in my head really came down to infectious versus neoplastic, but his CBC showed 20K lymphs with zero activity going in the PMN range, but a vast predominance of lymphs. This makes the diagnosis of leukemia cutis a virtual certainty.   Had it been infectious, we would have seen a much less lymphocytic, much more PMN-rich differential. Additionally, we had the comments from the pathologist regarding the SCC to base our opinion on.

Leukemias are proliferations of clonal populations of leukocytes (in this case lymphocytes) which are maturationally arrested. Leukemia cutis represents clonal proliferations in the skin which may be seen in AML, ALL, CML, CLL, as well as hairy cell leukemia and myelodysplastic syndrome.  If it is associated with AML or ALL, it has a very grim prognosis.