We describe a 19-year-old male patient who presented with recalcitrant erosions limited to the orolabial and genital mucosa for 18 months. The clinicopathologic diagnosis of paraneoplastic pemphigus was confirmed by indirect immunofluorescence staining of murine bladder epithelium, and the presence of IgG autoantibodies against envoplakin, periplakin, and 170 kDa protein. Enzyme-linked immunosorbent assay (ELISA) with desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1) recombinant proteins showed that the patient's sera were positive against Dsg3. Castleman's tumour was found in the pelvic cavity and resected completely. The orogenital erosions disappeared slowly after the resection of Castleman's tumour with the concomitant decrease in intercellular antibody titre and index values of Dsg ELISA. Although the patient was unaware of dyspnea on exertion, a notable air flow obstruction persisted over 17 months. The expiratory images of high resolution computed tomography showed air trapping, indicating the presence of asymptomatic but gradually progressive bronchiolitis obliterans.