Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. GISTs arise in the smooth muscle pacemaker interstitial cell of Cajal, or similar cells. They are defined as tumors whose behavior is driven by mutations in the KIT gene (85%), PDGFRA gene (10%), or BRAF kinase (rare). 95% of GISTs stain positively for KIT (CD117). Most (66%) occur in the stomach and gastric GISTs have a lower malignant potential than tumors found elsewhere in the GI tract.
A leiomyoma, also known as fibroids, is a benign smooth muscle tumor that very rarely becomes cancer (0.1%). They can occur in any organ, but the most common forms occur in the uterus, small bowel, and the esophagus. Polycythemia may occur due to increased erythropoietin production as part of a paraneoplastic syndrome.
Surface epithelial-stromal tumors are a class of ovarian neoplasms that may be benign or malignant. Neoplasms in this group are thought to be derived from the ovarian surface epithelium or from ectopic endometrial or Fallopian tube (tubal) tissue. Tumors of this type are also called ovarian adenocarcinoma. This group of tumors accounts for 90% to 95% of all cases of ovarian cancer. Serum CA-125 is often elevated but is only 50% accurate so it is not a useful tumor marker to assess the progress of treatment.
A glomus tumor is a rare neoplasm arising from the glomus body and mainly found under the nail, on the fingertip or in the foot. They account for less than 2% of all soft tissue tumors. The majority of glomus tumors are benign, but they can also show malignant features. Glomus tumors were first described by Hoyer in 1877 while the first complete clinical description was given by Masson in 1924.
Uterine fibroids, also known as uterine leiomyomas or fibroids, are benign smooth muscle tumors of the uterus. Most women have no symptoms while others may have painful or heavy periods. If large enough, they may push on the bladder causing a frequent need to urinate. They may also cause pain during sex or lower back pain. A woman can have one uterine fibroid or many. Occasionally, fibroids may make it difficult to become pregnant, although this is uncommon.
Leiomyosarcoma, is a malignant (cancerous) smooth muscle tumor. A benign tumor originating from the same tissue is termed leiomyoma. While it has been believed that leiomyosarcomas do not arise from leiomyomas, there are leiomyoma variants for which classification is evolving.
Phyllodes tumors, also cystosarcoma phyllodes, cystosarcoma phylloides and phylloides tumor, are typically large, fast-growing masses that form from the periductal stromal cells of the breast. They account for less than 1% of all breast neoplasms.
Anaplasia is a condition of cells with poor cellular differentiation, losing the morphological characteristics of mature cells and their orientation with respect to each other and to endothelial cells. The term also refers to a group of morphological changes in a cell that point to a possible malignant transformation.
The uterine sarcomas form a group of malignant tumors that arises from the smooth muscle or connective tissue of the uterus.
Atypia is a histopathologic term for a structural abnormality in a cell, i.e. it is used to describe atypical cells.
A malignant mixed Müllerian tumor, also known as malignant mixed mesodermal tumor (MMMT) is a cancer found in the uterus, the ovaries, the fallopian tubes and other parts of the body that contains both carcinomatous and sarcomatous components. It is divided into two types, homologous and a heterologous type. MMMT account for between two and five percent of all tumors derived from the body of the uterus, and are found predominantly in postmenopausal women with an average age of 66 years. Risk factors are similar to those of adenocarcinomas and include obesity, exogenous estrogen therapies, and nulliparity. Less well-understood but potential risk factors include tamoxifen therapy and pelvic irradiation.
Blue nevus is a type of melanocytic nevus. The blue colour is caused by the pigment being deeper in the skin than in ordinary nevi. In principle they are harmless but they can sometimes be mimicked by malignant lesions, i.e. some melanomas can look like a blue nevus.
In medicine, desmoplasia is the growth of fibrous or connective tissue. It is also called desmoplastic reaction to emphasize that it is secondary to an insult. Desmoplasia may occur around a neoplasm, causing dense fibrosis around the tumor, or scar tissue (adhesions) within the abdomen after abdominal surgery.
Endometrial stromal sarcoma is a malignant subtype of endometrial stromal tumor arising from the stroma of the endometrium rather than the glands. There are three grades for endometrial stromal tumors, as follows. It was previously known as endolymphatic stromal myosis because of diffuse infiltration of myometrial tissue or the invasion of lymphatic channels.
Ceruminous adenocarcinoma is a malignant neoplasm derived from ceruminous glands of the external auditory canal. This tumor is rare, with several names used in the past. Synonyms have included cylindroma, ceruminoma, ceruminous adenocarcinoma, not otherwise specified (NOS), ceruminous adenoid cystic carcinoma (ACC), and ceruminous mucoepidermoid carcinoma.
Reed’s syndrome is a rare inherited condition characterised by multiple cutaneous leiomyomas and, in women, uterine leiomyomas. It predisposes for renal cell cancer, an association denominated hereditary leiomyomatosis and renal cell cancer, and it is also associated with increased risk of uterine leiomyosarcoma. The syndrome is caused by a mutation in the fumarate hydratase gene, which leads to an accumulation of fumarate. The inheritance pattern is autosomal dominant.
Biphenotypic sinonasal sarcoma is a newly recognized, very rare, low grade malignant tumor of the nasal cavity which was formerly probably included in fibrosarcoma and synovial sarcoma cases. It was incorporated into the fourth edition of the World Health Organization Classification of Head and Neck Tumours, published in 2017.
Ectomesenchymal chondromyxoid tumor (ECT) is a benign intraoral tumor with presumed origin from undifferentiated (ecto)mesenchymal cells. There are some who think it is a myoepithelial tumor type.
Prostatic stromal tumour of uncertain malignant potential (PSTUMP) is a rare tumour of the prostate gland stroma that may behave benign or like cancer.
