Pathology wk 29-32: Lymphangioma, chondroid, Psommoma body

Lymphangioma: A benign, carvernous/cystic vascular lesion composed of dilated lymphatic channels.

- also called cystic hygroma

- common pediatric lesion
- associated with Turner's syndrome

- Carvenous/cystic lymphangioma of head and neck most frequent

- developmental malformation

- thin walled, dilated lymphatic vessels of different size, lined by a flattened endothelium and surrounded by lymphocytic aggregate. Lumina maybe empty or contain proteinaceous fluid, lymphocyte and sometimes erythrocytes. Larger vessels can be invested by a smooth muscle layer, and long standing lesions reveal interstitial fibrosis and stromal inflammation. Stromal mast cells are common and hemosiderin deposition is frequently seen.

Chondroid

Papillary thyroid carcinoma

- neoplastic papilla contain a central core of fibrovascular(occasionally just fibrous) tissue lined by one or occasionally several layers of cells with crowded oval nuclei.

- In contrast, hyperplasia of thyroid follicles may sometimes appear papillary change, there is infolding of the lining epithelium composed of columnar cells with basal round and uniform nuclei. There is either no central core or a core of edematous or myxomatous paucicellular stroma often including small follicles.

- Psommoma bodies that represent the "ghosts" of dead papillae are differentiated from dystrophic calcificaiton by lamellation. True psommoma bodies are formed by focal areas of infarction of the papilla and ensuing calcium deposition leading to lamellation. Usually present within the cores of papillae or in the tumor stroma, but not within the neoplastic follicles. Only rarely are psommoma bodies found in benign conditions of the thyroid.