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Case Reports

Abstract

Patient History

Dermatology was consulted for an 11-year-old presenting with a multiple-day history of blisters on the forearm, back, thighs, and vulva after an autologous stem cell transplant for medulloblastoma treatment due to concern for Stevens-Johnson syndrome (SJS) versus graft-vs-host disease (GVHD), versus bullous drug eruption. The patient was treated with carboplatin and thiotepa for pre-bone marrow transplant chemotherapy. On physical examination there were scattered non-erythematous tense bullae and erosions on upper extremities and linear tense bullae on medial thigh at sites of friction from the urinary catheter. There was no oral or ocular involvement. 

Biopsy

Punch biopsy of a tense bullae on the right medial thigh revealed superficial epidermal necrosis with rare dyskeratosis. The findings were consistent with a resolving interface process.

Laboratory Data

Laboratory tests were notable for anemia (hemoglobin - 7.9 g/dL), monocytosis (1.18 x10^9/L), and azotemia (blood urea nitrogen - 111 mg/dL). 

Diagnosis 

The clinical and pathological findings were consistent with thiotepa toxiderma (TT). TT is characterized by hyperpigmented patches, edematous plaques, erythema, and blistering, often in occluded areas due to thiotepa being excreted onto the skin by sweat. It is a rare adverse event with a poorly documented prevalence. TT may demonstrate eccrine gland necrosis, epidermal dysmaturation, and apoptotic keratinocytes. Histologically, this case mimicked SJS and GVHD due to the presence of partial-thickness epidermal necrosis.

Treatment

The patient was advised to apply Vaseline twice daily as needed and reassured that she did not need to discontinue any of her current medications.