Peripheral neuroblastic tumors arising from the sympathoadrenal lineage of neural crest during development include neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. Although some ganglioneuromas were once believed to arise independently of neuroblastoma, the International Neuroblastoma Pathology Committee now states that “all ganglioneuromas were…
Malignant Peripheral Nerve Sheath Tumor Malignant tumors arising from or displaying differentiation along the lines of the various elements of the nerve sheath (e.g., Schwann cell, perineurial cell, fibroblast) are collectively referred to as malignant peripheral nerve sheath tumors (MPNSTs).…
Benign peripheral nerve sheath tumors differ from other soft tissue tumors in several important respects. Most soft tissue tumors arise from mesodermally derived tissue and display a range of features consonant with that lineage. Nerve sheath tumors arise from tissues…
The synovial membrane forms the lining of joints, tendons, and bursae. In addition, its cells synthesize hyaluronate, a major component of synovial fluid, and facilitate the exchange of substances between blood and synovial fluid. The synovial membrane varies considerably in…
Perivascular tumors recapitulate the appearance of the modified myoid cells that support or invest blood vessels (i.e., glomus cell and pericyte). Sometimes referred to as perivascular myoid tumors, these include glomus tumor and its variants, myopericytoma, myofibroma/myofibromatosis, and sinonasal glomangiopericytoma…
The lymphatics are an extensive unidirectional system of blunt-ending vessels that regulate normal tissue pressure by retrieving excess fluid from the interstitium, transporting it to regional lymph nodes, and returning it to the venous system by way of the thoracic…
Angiosarcoma Angiosarcomas are malignant tumors that recapitulate many of the functional and morphologic features of normal endothelium. They vary from highly differentiated tumors resembling a hemangioma to anaplastic lesions difficult to distinguish from a poorly differentiated carcinoma or pleomorphic sarcoma.…
Vascular Tumors of Intermediate Malignancy The term hemangioendothelioma is the designation for vascular tumors that have a biologic behavior intermediate between a hemangioma and a conventional angiosarcoma. Tumors included in this group have the ability to recur locally and some…
The term hemangioma has been used broadly in the past to describe any benign, nonreactive vascular process with an increase in normal or abnormal-appearing vessels or simply abnormally configured vessels. Hemangiomas have been further subclassified pathologically, based on the predominant…
During the 1930s and 1940s, the diagnosis of adult or pleomorphic rhabdomyosarcoma was increasingly made, and most of the rhabdomyosarcomas reported during this period were of this type. These tumors occurred mainly in the muscles of the lower extremity and…