Low-grade papillary adenocarcinoma of minor salivary glands. Case report and literature review.

Low-grade papillary adenocarcinoma of minor salivary glands is rare and tends to occur in the palate. This tumor has distinct but rather deceptive histomorphologic features, which may cause erroneous diagnosis. An extensive English-language literature review revealed reports of 22 well-documented low-grade papillary adenocarcinomas. Six of these tumors (27%) recurred locally between 12 months and 19 years after initial treatment. Low-grade papillary adenocarcinoma appears to have more aggressive biologic behavior compared with other low-grade adenocarcinomas in this region. Four of the reported cases (17%) had cervical lymph node metastases at the time of presentation. We report an additional case and discuss the literature.

In situ distribution of the beta-subunit of platelet-derived growth factor receptor in nonneoplastic tissue and in soft tissue tumors.

The distribution of the beta-subunit of platelet-derived growth factor receptor (PDGFR-beta) was assessed by a sensitive immunoalkaline phosphatase technique using the monoclonal antibody PR7212. Frozen tissue sections of several nonneoplastic human tissues were stained along with 42 soft tissue sarcomas, 16 benign soft tissue proliferations, and 7 epithelial tumors. In all nonneoplastic tissue, there was intense labeling of cell processes of perivascular fibroblasts or pericytes in and about the walls of muscular blood vessels and of fibroblast cell processes around some glandular and ductal epithelia. No PDGFR-beta was found in the endothelial cells of muscular arteries and veins, but cells of uncertain identity within some capillaries were immunoreactive and the possibility that endothelial cells of some small capillaries express PDGFR-beta could not be excluded. In kidney there was strong labeling of glomerular mesangial cells and interstitial fibroblasts. Some histological types of soft tissue sarcomas were uniformly and strongly labeled with anti-PDGFR-beta, but other types were infrequently labeled or unreactive. The order of decreasing frequency and strength of labeling of the various types of benign and malignant soft tissue proliferations was as follows: benign fibromatosis and neurofibroma greater than malignant fibrous histiocytoma greater than liposarcoma greater than leiomyosarcoma greater than rhabdomyosarcoma. No tumor cell labeling was detected in epithelioid, synovial or clear cell sarcomas, leiomyomas, or carcinomas, but there was usually strong labeling of fibroblast and/or pericyte cell processes within tumor, especially around blood vessels. We conclude that PDGFR-beta is strongly expressed by vascular and stromal tissues of most tumors and normal organs and by tumor cells of several types of soft tissue tumors and proliferations, most notably those of fibroblastic origin.