1/4. Myoepitheliomas of the skin and soft tissues. Report of 12 cases.We describe 12 cutaneous and soft tissue myoepitheliomas, most of them in elderly patients. Morphologically the cutaneous and soft tissue myoepitheliomas revealed the same spectrum as their salivary gland counterparts. They were composed of a mixture of spindle, epithelioid and clear myoepithelial cells. Immunohistochemically they were positive to keratins and S-100 protein and reacted inconsistently with antibodies to smooth muscle actin. Morphologically they lacked any folliculo-sebaceous or apocrine differentiation. We believe that they are related to the eccrine type of cutaneous mixed tumours. Most cases had a benign behaviour, but 1 tumour metastasized, and the patient died of the tumour. Myoepitheliomas of soft tissues should be distinguished from other neoplasms with epithelial differentiation and from ossifying fibromyxoid tumour of soft parts, parachordoma and extraskeletal myxoid chondrosarcoma.- - - - - - - - - - ranking = 1keywords = mixed tumour (Clic here for more details about this article) |
2/4. Lipomatous mixed tumour of the skin: a histological, immunohistochemical and ultrastructural study.BACKGROUND: Mixed tumours are composed of an admixture of an epithelial/myoepithelial and usually a myxochondroid stromal component. adipocytes are found more rarely, and account for a minor part of the tumour. To date, only three cases of mixed tumour/pleomorphic adenoma of the salivary gland have been described, showing an extensive adipocyte content of more than 90% of the tumour tissue. Owing to this peculiarity, some authors have defined it as 'lipomatous pleomorphic adenoma'. We are not aware of previously reported similar lesions in the skin. OBJECTIVES: We report a case of a tumour that occurred as a 2 x 2 x 1.5 cm nodule in the scalp of a 65-year-old man. Analogies with salivary lipomatous pleomorphic adenoma, as well as histogenesis and differential diagnoses are discussed here. methods: A histological, immunohistochemical and ultrastructural study was performed. RESULTS: The tumour was well-circumscribed and showed a substantial mature adipose tissue component intermingled with epithelial cells arranged in ducts and branching tubules, embedded in a fibromyxoid stroma, which was diagnostic of a chondroid syringoma/mixed tumour. adipocytes strongly expressed S-100 protein and cytokeratin 14. Transitional elements from epithelial/myoepithelial cells into adipocytes were observed. They coexpressed cytokeratin 14, S-100 protein and vimentin, and showed lipid droplets, desmosome-type junctions, cytoplasmic tonofilaments and basal lamina. CONCLUSIONS: The tumour differed from lipomas with myxoid stroma and from lipoadenomas, which show non-proliferating normal sweat glands admixed with adipose tissue. Because of the similarity to lipomatous pleomorphic adenoma/mixed tumour of salivary glands, we suggest that it should be called 'lipomatous mixed tumour of the skin'.- - - - - - - - - - ranking = 7keywords = mixed tumour (Clic here for more details about this article) |
3/4. Malignant mixed tumour arising from minor salivary gland tissue of the right parapharyngeal space with metastasis to the scalp.A case of malignant mixed tumour arising from minor salivary gland tissue in the right parapharyngeal space with metastasis to the scalp is described. Both the clinical presentation and the histological picture were unusual. The simultaneous discovery of the primary parapharyngeal tumour and its scalp metastasis, the relatively young age of the patient (43 years-old), the origin of the tumour in minor salivary gland tissue, and the presence of a benign stromal component in the metastasis are features not commonly described in the three entities covered by the term "malignant mixed tumour". We believe this case represents a distinct variant, whose behaviour and progression have not been previously well documented.- - - - - - - - - - ranking = 6keywords = mixed tumour (Clic here for more details about this article) |
4/4. Malignant transformation of a benign cutaneous mixed tumour.Whilst benign cutaneous mixed tumour is common, malignant cutaneous mixed tumour is rare. There are only eleven accepted cases of the malignant counterpart in the literature. In none was there residual benign tumour tissue present to suggest that they arose from malignant transformation of the benign tumour. We report a very rare case of a malignant transformation of a benign cutaneous mixed tumour in an eighty-four year old female. Other unusual features in this case included considerable involvement of bone in the primary lesion and the histological picture of extreme pleomorphism and active mitoses, not seen in other reported cases of the malignant tumour.- - - - - - - - - - ranking = 7keywords = mixed tumour (Clic here for more details about this article) |