Pemetrexed-induced eccrine squamous syringometaplasia manifesting as pseudocellulitis (in a patient with non–small cell lung cancer)

CAR: cutaneous adverse reaction INTRODUCTION Pemetrexed (Alimta, Eli Lily and Company, Indianapolis, Indiana) is a multitargeted antifolate drug approved as a single agent or in combination with cisplatin for the treatment of some malignancies including advanced and metastatic nonsquamous nonesmall cell lung cancer and malignant pleural mesothelioma. Pemetrexed-related cutaneous adverse reactions (CARs) are frequently reported under the nonspecific term, skin rash. Nevertheless, specific patterns of CARs have been reported in the literature including alopecia, acute generalized exanthematous pustulosis, urticarial vasculitis, radiation recall dermatitis, toxic epidermal necrolysis, eyelid edema, and pityriasis lichenoideselike dermatitis. To reduce the incidence of CARs, the manufacturer recommends adjunct therapy with dexamethasone the day before, the day of, and the day after administration of pemetrexed. Cellulitis is defined as a non-necrotizing inflammation of the skin and subcutaneous tissue, usually from acute infection. The examining physician often identifies a distinct clinical picture comprising erythema, swelling, warmth, and tenderness of the affected skin. The term pseudocellulitis is used when the clinical picture is compatible with cellulitis but the inflammation is not from an infectious cause. This can sometimes confuse and mislead clinicians. Cases of pseudocellulitis have been well reported with gemcitabine. We present a case of pemetrexed-induced pseudocellulitis that showed eccrine squamous syringometaplasia on skin biopsy.