Cutaneous paraneoplastic pemphigus syndrome associated with undifferentiated uterine sarcoma

•This case report identifies a non-classical paraneoplastic pemphigus foliaceous cause by an undifferentiated uterine sarcoma.•This patient’s paraneoplastic pemphigus (PNP) was resistant to treatment with azathioprine, dapsone, mupirocin cream, or betamethasone ointment, but stabilized with prednisone and rituximab per lymphoma protocol at 375 mg/m2 weekly for one month.•Dermatological symptom resolution was noted by the patient after surgical resection, with a corresponding drop in anti-Dsg1 IgG from 230u to 32u.•No PNP cases exist that expressed only anti-Dsg1 IgG like this patient.•This patient lacked mucosal involvement and anti-Dsg3 IgG, agreeing with literature suggesting their correlation.