Embryonal rhabdomyosarcoma (ERMS) is a rare histological form of cancer

Cancer

Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

 of connective tissue wherein the mesenchymally-derived malignant

Malignant

Malignancy is the tendency of a medical condition, especially tumors, to become progressively worse and to potentially result in death. Malignancy in cancers is characterized by anaplasia, invasiveness, and metastasis...

 cells resemble the primitive developing skeletal muscle of the embryo. It is the most common soft tissue sarcoma

Sarcoma

A sarcoma is a cancer that arises from transformed cells in one of a number of tissues that develop from embryonic mesoderm. Thus, sarcomas include tumors of bone, cartilage, fat, muscle, vascular, and hematopoietic tissues...

 occurring in children.

Classification

ERMS is the more common of two major subtypes of rhabdomyosarcoma

Rhabdomyosarcoma

A rhabdomyosarcoma is a type of cancer, specifically a sarcoma , in which the cancer cells are thought to arise from skeletal muscle progenitors. It can also be found attached to muscle tissue, wrapped around intestines, or in any anatomic location...

, the other being alveolar rhabdomyosarcoma

Alveolar rhabdomyosarcoma

Alveolar rhabdomyosarcoma is a type of rhabdomyosarcoma characterized by its appearance, which is similar to the alveoli of the lungs.It can be associated with a fusion protein between PAX3 and FKHR ....

.

It has been informally classified as a "small round blue cell tumor" because of the characteristic microscopic appearance of its cells after histological staining with hematoxylin and eosin.

Prognosis and survival

The prognosis for rhabdomyosarcoma has improved greatly in recent decades, with over 70% of victims surviving for five years after diagnosis.