The review included 163 cases of paraneoplastic pemphigus (PNP) reported between 1990 and 2003, including a new unique case of PNP associated with occult breast cancer and an ovarian cyst of borderline malignancy. Hematologic-related neoplasms or disorders were associated with 84% of the cases, with non-Hodgkin lymphoma (38.6%) as the most frequent, followed by chronic lymphocytic leukemia (18.4%) and Castleman's disease (18.4%). The non-hematologic neoplasms comprised 16% of all cases: epithelial origin-carcinoma (8.6%), mesenchymal origin-sarcoma (6.2%), and malignant melanoma (0.6%). Carcinoma cases comprised 58% of the non-hematologic neoplasms. Carcinoma cases (n = 14) consisted of adenocarcinoma (n = 7), squamous cell carcinoma (n = 2), multiple skin tumors probably basal cell carcinoma (n = 1), and bronchogenic carcinoma (n = 1). Of the 10 (6.2%) sarcoma cases, there was one case each of leiomyosarcoma, liposarcoma, malignant nerve sheath tumor, poorly differentiated sarcoma, reticulum cell sarcoma, dendritic cell sarcoma and inflammatory myofibroblastic tumor. The oral mucosa was involved in all of cases. Isolated oral ulcerations were the first sign in 45% of the cases. Diffuse and persistent oral ulcerations with a progressive course could be a sign of malignancy, either recognized or occult. In the absence of a clear diagnosis, malignancy should be suspected and extensive work-up performed. The full spectrum of signs of PNP may not be present initially. Repeated biopsies, direct and indirect immunofluorescence as well as screening indirect immunofluorescence on murine bladder are required for diagnosis. Clinicians should be highly suspicious when signs and symptoms suggestive of PNP are present in cancer patients, of hematologic and non-hematologic origin.