Disseminate intradermal bacterial colonization presenting as palpable purpura in lymphoblastic leukemia

A patient with acute lymphoblastic leukemia suddenly developed a disseminated monomorphic eruption of purpuric papules. The papules were initially thought to be lesions of vasculitis, leukemia cutis, or septic emboli. Histologic study, however, revealed large focal colonies of gram-positive cocci within the dermis. It is postulated that a bacteremia of antibiotic-resistant cocci led to dissemination of these organisms into a virtually defenseless skin. The patient's pancytopenia and consequent immune paralysis are viewed as accounting for this focal bacterial colonization and for the remarkable absence of clinical and histologic inflammatory response. Such hematogenous noninflammatory bacterial colonization of the skin must be added to the differential diagnosis of palpable purpura.