Leiomyoma (overview)D21.M4

Virchow, 1854; Kloepfer, 1958

Benign, congenital or acquired cutaneous tumour originating from smooth muscle cells of cutaneous vessels or the arrectores pili muscle (more rarely the tunica dartos and smooth muscle cells of the nipples and vulva), which can occur either singly or multiply.

It's gonna be 3 guys and different. The association with internal tumors is clinically significant. :

• Piloleiomyoma (starting from the arrector pili of the hair follicle)
  • Solitary leiomyoma...
  • Leiomyomas of the nipple and the areola mamillae
  • Multiple Leiomyomas (Leiomyomatosis)
  • Segmental cutaneous leiomyomatosis
  • Hereditary leiomyomatosis with leiomyomas of the uterus (MCUL = multiple cutaneous and uterine leiomyomatosis)
  • Hereditary leiomyomatosis with renal cell car cinoma (HLRCC = hereditery leiomyomatosis and renal cell carcinomas)
• Angioleiomyoma
• Genital leiomyomas (dartoid leiomyomas, starting from the tunica dartos)

In hereditary forms (hereditary multiple leiomyomas of the skin), autosomal-dominantly inherited mutations of the FH gene (fumarate hydratase gene; gene locus: 1q42.3-43) are detected. The FH gene encodes fumarate hydratase, which catalyzes the reaction of fumarate to maleate in the citric acid cycle. The gene is also thought to have properties as a tumor suppressor gene.

Hereditary leiomyomatosis is associated with multiple leiomyomas of the uterus as well as papillary renal cell carcinomas(hereditary leiomyomatosis with renal cell carcinoma).

Solitary papules or nodules are less common. Mostly multiple, often grouped, but also arranged in strips (in the Blaschko lines), up to 0.5 cm in size, skin-colored to brownish, often pressure-painful (see below the acronym ANGLES for other painful tumors of the skin) or reactive to temperature, slightly raised nodules. See also myomatosis cutis miliaris. Less common is a flat, plate-like infestation (see illustration), which can result in plaques measuring 8.0-10.0 cm. Smooth muscle hamartomas (mostly piloleiomyomas) are often associated with a Becker nevus.

Usually blurred tumour with irregularly shaped, interwoven bundles of smooth muscle cells separated from the epidermis by a narrow border zone. Characteristic features include spindly nuclear formations, a differently pronounced nuclear polymorphism. It is not uncommon to encounter single multinuclear giant cells, often with myxoid stroma and perivascular sclerosis (ancient leiomyoma, bizarre leiomyoma) as well as a honeycomb-like loosening of the cytoplasm (perinuclear halo formation) as an important differential diagnostic sign. S.a.u. Angioleiomyoma; see myofibroma below. In contrast to leiomyosarcoma, mitoses are absent.

Classification of leiomyomas according to origin and localization

The tunica dartos (from gr. dartos, "skinned", "like raw meat") is a thin layer of smooth muscle fibers of the scrotum. Among other things, it serves to regulate the temperature of the testicles.

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