grotesque

hairy polyp?

An "Immature Teratoma" is a rare type of malignant (cancerous) germ cell tumor that can contain several types of tissue such as hair, muscle, and bone. ++

Malignant tumors are the cancerous type.

a metastatic neoplasm?

I could well be wrong, but I don't know of any malignant tumours that contain hair. However, it is possible for people to have benign cysts which contain hair, and even teeth.

Dermoid cyst of the ovary : A bizarre tumor, usually benign, in the ovary that typically contains a diversity of tissues including hair, teeth, bone, thyroid, etc. A dermoid cyst develops from a totipotential germ cell (a primary oocyte) that is retained within the egg sac (ovary). Being totipotential, that cell can give rise to all orders of cells necessary to form mature tissues and often recognizable structures such as hair, bone and sebaceous (oily) material, neural tissue and teeth. teratomas (which are usually benign) were thought to originate in some sort of embryonic or quasi-embryonic cell gone wrong. But most experts now consider them a type of germ-cell tumor--in this case a tumor involving an egg. Though the egg is unfertilized, tumor-driven cell division results in a lot of the same stuff you see in a developing fetus, including cartilage, bone, teeth, hair, brain tissue, and sometimes even bowel, skull, vertebrae, and eyes. Teratomas most fascinating quality, is their capacity to generate a smorgasbord of human tissue varieties, including bones, skin and ligaments. As a result, researchers testing a new medicine on a cancer-seeded teratoma can gauge what effects the drug will have on different cell types without enlisting human subjects. A teratoma is a type of rare congenital tumor. It is seen predominantly in girls with a ratio of four females to one male. It is the most common tumor of the newborn with an incidence of 1 in 40,000 live births. They also occur more frequently in twins or in families where there is a history of twins. The name teratoma in Greek means "monster tumor". In the newborn, the most common congenital tumor is a sacrococcygeal (tail bone) tumor. Since the tumor is often visible from the outside of the body, diagnosis is made immediately and treatment and/or surgery are initiated early, making the prognosis for this type of tumor very favorable. ovarian teratocarcinomas have been found that have grown hair and teeth. Typically, teratocarcinomas of the testes are less differentiated than other types and are, therefore, characteristically the most common variety to serve as sources for embryonal carcinoma cells intended for research purposes.