Smooth muscle tumours show a smooth muscle differentiation. There are two main types of smooth muscle tumour: the benign leiomyoma and the malignant leiomyosarcoma.

Smooth muscle tumor of uncertain malignant potential, abbreviated STUMP, is an uncommon tumor of the uterine smooth muscle that may behave like a benign tumor or a cancerous tumor.

This tumor should not be confused with the prostatic stromal tumor of uncertain malignant potential which may be abbreviated the same way ("STUMP").

The Bell criteria were developed to help categorize them and differentiate them from their main differential diagnoses, leiomyosarcoma and uterine leiomyoma.

The most common symptom of the papillary tumor is a headache. Because headaches are so common, most people think nothing of it. This is why brain tumors are so dangerous. There are not a lot of symptoms that go along with them so people tend to wait a long time before seeking medical help. Most of the time people will go see a doctor when their headaches become consistent and start to never go away. This symptom however occurs secondary to hydrocephalus, which is a result from compression of the cerebral aqueduct. The cerebral aqueduct is a narrow channel in the midbrain, which connects the third and fourth ventricles. When a tumor blocks the pathway of the cerebrospinal fluid, this will cause headaches in the patient. Often when hydrocephalus occurs, a shunt is put in place in order to alleviate the pressure. In one case study, an endoscopic third ventriculostomy was performed as a first line procedure to treat the hydrocephalus and also for diagnostic purposes.

In some cases, patients have had progressive diplopia, or double vision. Also, although not in all cases, patients sometimes suffer from nausea and vomiting.

Patients present with a slow-growing, painless, solitary mass, usually of the subcutaneous tissues. It is much less frequently noted in the intramuscular tissue. It is not uncommon for symptoms to be present for years.

Benign neoplasm with "BROWN FAT" is noted.

IPMs present as painless lymphadenopathy. They usually are found in the inguinal region and grow slowly.

The signs and symptoms are non-specific, i.e. it is not possible to diagnose an IPM from the symptoms and manner in which they present.

The main (clinical) differential diagnosis of IPM is metastatic cancer, e.g. squamous cell carcinoma, malignant melanoma, adenocarcinoma.

Myosarcoma is a malignant muscle tumor. People with myosarcoma often wake up with the feeling as if they had a cramp during their sleep.

Leiomyosarcoma is sarcoma of smooth muscle, and rhabdomyosarcoma is sarcoma of striated muscle. However, the term myosarcoma itself still appears in the literature.

This lesion has been called a fetal lipoma, lipoma of embryonic fat or a lipoma of immature fat.

Glomus tumors are usually solitary and small lesions. The vast majority are found in the distal extremities, particularly in the hand, wrist, foot, and under the fingernails.

They are often painful, and the pain is reproduced when the lesion is placed in cold water.

These tumors tend to have a bluish discoloration, although a whitish appearance may also be noted. Elevation of the nail bed can occur.

In rare cases, the tumors may present in other body areas, such as the gastric antrum or glans penis. Treatment is essentially the same.

The exact incidence of glomus tumors is unknown. The multiple variant is rare, accounting for less than 10% of all cases. The probable misdiagnosis of many of these lesions as hemangiomas or venous malformations also makes an accurate assessment of incidence difficult.

- Sex:

Solitary glomus tumors, particularly subungual lesions, are more common in females than in males. Multiple lesions are slightly more common in males.

- Age:

Solitary glomus tumors are more frequent in adults than in others. Multiple glomus tumors develop 11–15 years earlier than single lesions; about one third of the cases of multiple tumors occur in those younger than 20 years. Congenital glomus tumors are rare; they are plaquelike in appearance and are considered a variant of multiple glomus tumors.

Intranodal palisaded myofibroblastoma, abbreviated IPM, is a rare primary tumour of lymph nodes, that classically presents as an inguinal mass.

It afflicts predominantly males of middle age.

Leiomyosarcoma, also referred to as LMS, is a malignant (cancerous) smooth muscle tumor. A benign tumor originating from the same tissue is termed leiomyoma. It is also important to note that while it has been believed that leiomyosarcomas do not arise from leiomyomas, there are leiomyoma variants for which classification is evolving.

About 1 person in 100,000 gets diagnosed with LMS each year. Leiomyosarcoma is one of the more common types of soft-tissue sarcoma, representing 10 percent to 20 percent of new cases. (Leiomyosarcoma of the bone is more rare.) Sarcoma is rare, consisting of only 1 percent of cancer cases in adults. Leiomyosarcomas can be very unpredictable. They can remain dormant for long periods of time and recur after years. It is a resistant cancer, meaning generally not very responsive to chemotherapy or radiation. The best outcomes occur when it can be removed surgically with wide margins early, while small and still in situ.

The most common adverse effect is pain, which is usually associated with solitary lesions. Multiple tumors are less likely to be painful.

In one report, a patient with more than 400 glomus tumors had thrombocytopenia as a result of platelet sequestration (i.e. Kasabach-Merritt syndrome).

Malignant glomus tumors, or glomangiosarcomas, are extremely rare and usually represent a locally infiltrative malignancy. However, metastases do occur and are usually fatal.

Papillary tumors of the pineal region (PTPR) were first described by A. Jouvet et al. in 2003 and were introduced in the World Health Organization (WHO) classification of Central Nervous System (CNS) in 2007. Papillary Tumors of the Pineal Region are located on the pineal gland which is located in the center of the brain. The pineal gland is located on roof of the diencephalon. It is a cone shaped structure dorsal to the midbrain tectum. The tumor appears to be derived from the specialized ependymal cells of the subcommissural organ. Papillary tumors of the central nervous system and particularly of the pineal region are very rare and so diagnosing them is extremely difficult.

APAs are characterized by glands with abnormal shapes that: (1) often have squamous metaplasia, and (2) are surrounded by benign smooth muscle. Nuclear atypia, if present, is mild.

The microscopic differential diagnosis includes endometrial carcinoma and endocervical adenocarcinoma.

Smooth muscle cells make up the involuntary muscles, which are found in most parts of the body, including the uterus, stomach and intestines, the walls of all blood vessels, and the skin. It is therefore possible for leiomyosarcomas to appear at any site in the body. They are most commonly found in the uterus, stomach, small intestine and retroperitoneum.

Uterine leiomyosarcomas come from the smooth muscle in the muscle layer of the uterus. Cutaneous leiomyosarcomas derive from the pilo-erector muscles in the skin. Gastrointestinal leiomyosarcomas might come from smooth muscle in the GI tract or, alternatively, also from a blood vessel. At most other primary sites—retroperitoneal extremity (in the abdomen, behind the intestines), truncal, abdominal organs, etc.—leiomyosarcomas appear to grow from the muscle layer of a blood vessel (the tunica media). Thus a leiomyosarcoma can have a primary site of origin anywhere in the body where there is a blood vessel.

The tumors are usually hemorrhagic and soft and microscopically marked by pleomorphism, abundant (15–30 per 10 high power fields) abnormal mitotic figures, and coagulative tumor cell necrosis. There is a wide differential diagnosis, which includes spindle cell carcinoma, spindle cell melanoma, fibrosarcoma, malignant peripheral nerve sheath tumor and even biphenotypic sinonasal sarcoma.

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.

Desmoplasia is usually only associated with malignant neoplasms, which can evoke a fibrosis response by invading healthy tissue. Invasive ductal carcinomas of the breast often have a scirrhous, stellate appearance caused by desmoplastic formations.

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.

The word is from "" + "" + "", "smooth-muscle tumor".

Solid pseudopapillary tumours are typically round, well-demarcated, measuring 2–17 cm in diameter (average 8 cm), with solid and cystic areas with hemorrhage on cut sections.

An muscle tissue neoplasm is a neoplasm derived from muscle.

An example is myoma.

Multiple cutaneous leiomyomas, also known as Pilar leiomyomas, arise from the arrectores pilorum muscles, and are made up of a poorly circumscribed proliferation of haphazardly arranged smooth muscle fibers located in the dermis that appear to infiltrate the surrounding tissue and may extend into the subcutis.

Sometimes associated with uterine leiomyomas (a combination known as multiple cutaneous and uterine leiomyomatosis, MCUL), these lesions may also be a manifestation of the hereditary leiomyomatosis and renal cell cancer syndrome.

A solid pseudopapillary tumour (also known as solid pseudopapillary neoplasm or, more formally, solid pseudopapillary tumour/neoplasm of the pancreas) is a low-grade malignant neoplasm of the pancreas of architecture that typically afflicts young women.

Pathologists classify serous cystic neoplasms into two broad groups. Those that are benign, that have not spread to other organs, are designated "serous cystadenoma". Serous cystadenomas can be further sub-typed into microcystic, oligocystic (or macrocystic), solid, mixed serous-endocrine neoplasm, and VHL-associated serous cystic neoplasm. This latter classification scheme is useful because it highlights the range of appearances and the clinical associations of these neoplasms. Serous cystic neoplasms that have spread ("metastasized") to another organ are considered malignant and are designated "serous cystadenocarcinoma".

Uterine fibroids are leiomyomata of the uterine smooth muscle. As other leiomyomata, they are benign, but may lead to excessive menstrual bleeding (menorrhagia), often cause anemia and may lead to infertility.

A rare form of these tumors is uterine lipoleiomyoma—benign tumors consisting of a mixture of adipocytes and smooth muscle cells. Uterine lipoleiomyomata have been observed together with ovarian and other pathologies and some of them may develop into liposarcoma. These tumors are monoclonal, and non-random chromosomal abnormalities have been seen in 40% of the tumors.

Medulloepithelioma is a rare, primitive, fast-growing brain tumour thought to stem from cells of the embryonic medullary cavity. Tumours originating in the ciliary body of the eye are referred to as embryonal medulloepitheliomas, or diktyomas.

A highly malignant undifferentiated primitive neuroepithelial tumour of children, medulloepithelioma may contain bone, cartilage, skeletal muscle, and tends to metastasize extracranially.

Medulloepithelioma most commonly affect children between 6 months and 5 years; rarely, this tumour may occur congenitally or beyond this age range. Incidence is equal in males and females.

Hyalinizing clear cell carcinoma, abbreviated HCCC, is a rare malignant salivary gland tumour, with a good prognosis, that is usually found on the tongue or palate.