Case Presentation: A 34-year-old male presented with 3 months of sores on his oral mucous membranes, rash, and a 50 lb weight loss felt to be due to pain with eating. He was seen by various providers in the outpatient setting and took courses of Valacyclovir, Azithromycin, and steroids without improvement. On initial presentation, there were extensive ulcerations on his lips, buccal mucosa, and tongue as well as blanching erythematous macules and papules (on trunk more than extremities). An intraoral biopsy of a mucosal lesion showed lichenoid mucositis. Punch biopsies of his body rash showed interface dermatitis. The patient was started on IV steroids, mucositis mouthwashes, and topical steroid creams, but his rash and sores did not improve. Given his significant weight loss, there was concern for malignancy, and a pan-CT showed marked retroperitoneal lymphadenopathy. A PET/CT confirmed hypermetabolic lymphadenopathy in the abdomen and mesentery. Surgical oncology performed an excisional biopsy of a mesenteric lymph node with results revealing follicular lymphoma. The patient was ultimately diagnosed with paraneoplastic pemphigus (PNP), and he was initiated on chemotherapy for lymphoma.
Discussion: PNP is a rare and highly fatal autoimmune blistering disease. It is characterized by severe oral lesions with cutaneous and systemic involvement, specifically in the lungs as bronchiolitis obliterans. Its skin lesions are similar to SJS/TEN, erythema multiforme, drug reactions, and pemphigus vulgaris, making a paraneoplastic pemphigus diagnosis difficult. PNP is commonly associated with malignancy, especially lymphoproliferative diseases, with a mortality rate as high as 80%. Autoantibodies triggered by the tumor attack the epithelial and mucosal layers of the skin and respiratory tract, manifesting as blisters/ulcers and respiratory distress respectively. Treatment of PNP involves treating the malignancy itself with resection of the tumor leading to a better prognosis. Systemic steroids and immunosuppressive agents, such as Rituximab, can also be used.
Conclusions: A blistering or desquamating rash can be confusing and difficult to diagnose as a hospitalist due to the heterogeneity and infrequency of its presentation. An early consultation with Dermatology can help ensure a correct diagnosis. Treatment of a blistering rash usually involves ordering antimicrobials for infections, such as HSV or VZV, or steroids if it is autoimmune in nature. However, it is important to look at the overall clinical picture and not focus only on treating the rash itself as an underlying malignancy can be overlooked. In PNP, a timely diagnosis and removal of the tumor can lead to an improved outcome.