Odontogenic cysts are one of the commonest bone destroying lesions of the maxillofacial skeleton, with the inflammatory radicular cyst being the commonest jaw cyst. Explants of radicular cysts produce an interleukin-1-like activity which could explain the osteolysis seen with these tumours though the cellular source of this osteolytic activity is unknown. In the present study, cytokines with known inflammatory and osteolytic activity: interleukin-1 (IL-1), tumour necrosis factor (TNF), interleukin-6 (IL-6), and the chemotactic cytokine interleukin-8 (IL-8) have been localized immunocytochemically in radicular cysts. The cellular adhesion receptors ICAM-1 and ELAM-1 have also been immunolocalized. All specimens showed positive staining for IL-1 (alpha and beta) and IL-6, with these cytokines being located in epithelial and vascular endothelial cells. Only two specimens demonstrated TNF and IL-8 staining, which was located in macrophages. All specimens demonstrated ELAM-1 staining in endothelium and ICAM-1 staining in epithelium, endothelium and mononuclear cells. These findings show that radicular cysts contain two bone-modulating cytokines, IL-1 and IL-6, and that these appear to be synthesized mainly by the epithelial cells. Cysts also contain a proportion of activated blood vessels whose endothelial cells express the cellular adhesion receptors ICAM-1 and ELAM-1.

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A 54 year old man developed an unusual lipoma in the patellar tendon, consisting of a fibro-adipose component and a chondro-osseous component. The fibro-adipose component contained mature adipocytes, lipoblasts, and fibroblasts; the chondro-osseous component showed typical endochondral bone formation. Molecular analysis showed that the identical HMGA2-LPP fusion transcript-characteristic of lipoma, parosteal lipoma, and pulmonary chondroid hamartoma-was detectable in the both components.

We present three cases of so-called mesothelial/monocytic incidental cardiac excrescences (MICE) of the heart and a brief review of related literature. Case 1 was a 51-year-old woman who underwent mitral- and aortic-valve replacement. A tissue sample was submitted as a thrombus attached to the left atrial endocardium. Case 2 was a 69-year-old woman who underwent mitral-valve replacement. The sample was incidentally obtained as whitish clot-like fragments, but its exact origin was not known. Case 3 was a 68-year-old woman who underwent mitral-valve replacement for suspected infective endocarditis. The sample adherent to the pericardium was removed after valvular surgery. Histologically, these lesions were composed of a mixture of plump histiocytoid cells, a papillary arrangement of cuboidal cells, various sized vacuoles, and fibrin. The nests of cuboidal cells resembled cancer cells but showed features of mesothelial cells and no proliferative activity, immunohistochemically or ultrastructurally. In all cases, a suction tube placed in the left atrium was occasionally used to remove overflowing intrapericardial fluid during the surgery. The tip of the suction tube was covered with spiral wire, which is likely to transfer the stripped pericardial mesothelial cells to the left atrium. The significance of MICE is their possibility of being misdiagnosed as metastatic carcinoma by pathologists and a risk of arterial embolization by mesothelial debris clinically.

The purpose of this study was to test the hypothesis that odontogenic cysts can be induced by periapical infection. Pulp extirpation and reaming beyond the root apices were performed in 53 lower first molars in 27 Sprague-Dawley rats. The cavities were left open to allow continuous contamination by oral bacteria. Animals were killed at 6 and more than 8 months after operation. Odontogenic cysts were found in association with 8/53 teeth in 6 animals. Histologically, cysts were observed around the lower incisors below the first molars. The cyst wall consisted of fibrous connective tissue with inflammation and was lined with keratinized squamous epithelium. The cyst cavity contained a mass of keratin and necrotic debris. These results support the hypothesis that inflammatory stimulation from the apices can cause cystic changes in the enamel epithelium of underlying teeth.