'Revertant' DCIS in human axillary breast carcinoma metastases.

Recent experimental evidence obtained in Scid mice has suggested that the metastatic process is in large part epigenetically regulated and undergoes partial reversion once the metastatic process is completed: the metastatic colonies become more engaged in the process of growing in situ than actively metastasizing. Based on this experimental evidence, examples were sought of metastatic human cancers where similar reversion to an in situ growth state was occurring. Review of 200 cases of metastatic human breast cancer revealed a 21 per cent incidence of reversion to a ductal carcinoma in situ (DCIS) growth pattern within axillary nodal metastases.

A case of juxta-articular myxoma of the knee.

This 9-year-old girl presented with a painful mass in the posterolateral aspect of her right knee. Excisional biopsy of the mass revealed a juxta-articular myxoma. The differential diagnosis for such an intra- or periarticular mass should include meniscal cyst, parameniscal cyst, ganglion cyst, juxta-articular myxoma, focal nodular PVNS, and desmoid tumor.

Case report 878: Densely calcifying synovial sarcoma of the hip metastatic to the lungs.

We discuss a patient with an occult, densely calcified synovial sarcoma of the hip who came to clinical attention because of pulmonary metastases. When synovial sarcomas present with dense and conglomerate calcification, they may be confused with benign processes such as myositis ossificans or tumoral calcinosis. Malignancies such as extraskeletal osteogenic sarcoma, extraskeletal chondrosarcoma, and mesenchymal chondrosarcoma must also be considered in the differential diagnosis.

Malignant clear cell hidradenoma of the upper lip.

Malignant clear cell hidradenoma is an uncommon tumor of eccrine sweat gland origin that has a predilection for the head and neck. It is characterized by an indolent growth pattern yet frequently recurs following surgical excision and has a high incidence of regional and distant metastases. A case of recurrent malignant clear cell hidradenoma of the upper lip is presented.