Histopathologic examination revealed basket-weave keratin with focal parakeratosis containing collections of serum and inflammatory cells. The epidermis demonstrated irregular acanthosis, spongiosis, focal spongiotic microvesiculation with occasional eosinophils, and underlying papillary dermal edema, focal hemorrhage, and superficial and deep perivascular and interstitial infiltrates of lymphocytes and eosinophils. Bacterial, mycobacterial, and fungal cultures were negative. These findings were consistent with a spongiotic drug eruption due to parenteral phytonadione injections. The plaques gradually resolved over several weeks, although the sites continued to be intermittently pruritic 15 months after presentation.
Indurated Plaques on the Arms of a 52-Year-Old Man. Arch Dermatol. 2001;137(7):957-962. doi: