Leiomyoma of the skin: causes, symptoms, diagnosis, treatment

Leiomyoma of the skin (synonym: angioleiomyoma) is a benign tumor of smooth muscles.

There are three types of this tumor: leiomyoma, which develops from the muscle that raises the hair; dartoideum (genital), which originates from the smooth muscles of the scrotum, female external genitalia, or the muscles that compress the nipple of the mammary glands; angioleiomyoma, which develops from the muscular elements of small vessels of the skin.

Leiomyoma, developing from the muscle that raises the hair, is small, dense, reddish, reddish-brown or the color of normal skin nodular or plaque-like elements, located in groups or linearly, most often on the extremities. As a rule, painful. Solitary leiomyoma has the same appearance, but the elements are much larger.

Causes and pathogenesis of skin leiomyoma. According to histogenesis, there are currently 3 types of skin leiomyomas, each characterized by clinical and histomorphological features.

• Type I - multiple leiomyomas developing from the smooth, erector hair, or diagonal muscles.
• Type II - dartoid (genital) solitary leiomyomas developing from the tunica dartos of the scrotum and smooth muscles of the mammary nipples.
• Type III - salt-bearing angioleiomyomas that develop from the muscular walls of the occluding arteries and smooth muscle elements of the walls of small vessels.

Some scientists believe that leiomyoma is more of a developmental defect than a neoplasm. There are isolated descriptions of familial leiomyoma, which allows us to consider this disease to be genetically determined.

Symptoms of cutaneous leiomyoma. Cutaneous leiomyoma is common in men. The affected element is a hemispherical, dense nodule of round or oval shape, the size of a pinhead to a lentil, large bean or larger, of a stagnant red, brownish, bluish-reddish color. A characteristic feature of cutaneous leiomyomas is their sharp pain under the influence of mechanical irritation (friction from clothing, scratching, pressure or touch) and cooling. The pain syndrome is caused by the pressure of nerve cells by the leiomyoma. Unbearable pain is often accompanied by dilated pupils, decreased blood pressure, and pale skin. Leiomyomas are usually multiple in nature and are localized on the face, neck, trunk and limbs, and are more often prone to grouping.

Histopathology. Leiomyoma consists of intertwined bundles of smooth muscle fibers separated by connective tissue layers. The cells have hyperchromatic nuclei, the number of vessels is reduced, and the number of nerve fibers is increased.

Pathomorphology. The tumor node of this type of leiomyoma is clearly delimited from the surrounding dermis and consists of thick bundles of smooth muscle fibers intertwined with each other, between which there are narrow layers of connective tissue. When stained using the Van Gieson method, the muscle bundles are stained yellow, and the connective tissue is red. A tumor developing from diagonal mice, without clear boundaries, has a similar structure, but the muscle fiber bundles are somewhat thinner and lie more loosely. Between the muscle bundles in the sparse connective tissue there are capillary vessels, sometimes with focal lymphohistiocytic infiltrates. Edema and dystrophic changes may be observed.

Dartoid leiomyoma is a solitary, painless, brownish-red node with a diameter of about 2 cm. Histologically, it differs little from leiomyoma developing from the muscle that raises the hair.

Angioleiomyoma is usually solitary, slightly elevated above the skin surface, covered with unchanged or reddish-blue skin, painful to palpation. Several elements may be found in a limited area, localized more often on the extremities, mainly near the joints.

Pathomorphology. Angioleiomyoma differs from other types of leiomyomas in that it consists of a dense interweaving of bundles of thin and short fibers, located in some places randomly, in some places in the form of concentric structures or swirls. The tumor tissue contains many cells with elongated nuclei that are intensely stained with hematoxylin and eosin. Among these elements, many vessels with an indistinct muscular membrane are found, directly passing into the tumor tissue, due to which the vessels look like slits located between the bundles of muscle fibers. Depending on the nature of the predominant vascular structures, four main types of angioleiomyoma structure can be distinguished. The most common are arterial angioleiomyomas, then venous and mixed, as well as poorly differentiated angioleiomyomas, in which a few vessels are determined, mainly with slit-like lumens. Some angioleiomyomas may show similarities with Barre-Masson glomus angiomas. They are characterized by the presence of "epithelioid" cells, which make up the bulk of the tumor. At later stages, various secondary changes may be detected in angioleiomyomas, such as a sharp expansion of blood vessels, proliferation of connective tissue, leading to sclerosis, hemorrhage with subsequent formation of hemosiderin.

Histogenesis. Electron microscopy has shown that leiomyomas from the muscles that raise the hairs consist of bundles of muscle cells of a normal appearance. They have a centrally located nucleus surrounded by the endoplasmic reticulum and mitochondria, and a large number of bundles of myofilaments on the periphery. Each muscle cell is surrounded by a basal membrane. Among them are nerve fibers in a state of twisting and disintegration of the myelin layer, apparently as a result of their compression by muscle cells. Some authors explain the painfulness of these tumors by such changes in nerve fibers, while others believe that the painfulness is a result of muscle contractions. A.K. Apatenko (1977), studying the histogenesis of angioleiomyomas, showed that the source of development of this type of tumor is the occluding arteries, as evidenced by the characteristic structure of the vessels (the presence of a longitudinal muscle layer, epithelioid cells, stellate lumens) and pain.

Leiomyosarcoma is rare. It can occur at any age, including in the first months of life. It is located in the deep layers of the skin, reaching large sizes, sometimes protruding significantly above the skin surface, and occasionally ulcerating. It is most often located on the lower extremities, then on the head and neck. The tumor is usually solitary, but multiple tumors also occur.

Pathomorphology. With a longer and less malignant course, the tumor structure resembles that of benign leiomyoma, differing from it by a noticeable proliferation of spindle-shaped elements and the presence of areas of nuclear polymorphism. With a more malignant variant, a large number of anaplastic hyperchromic nuclei are found in the tumor, sometimes located in groups, forming multinuclear symplasts, many unevenly scattered mitoses, as well as infiltrating growth into the underlying tissues.

Differential diagnosis should be made with fibromas, angiomas, fibrosarcomas, epitheliomas, leiomyosarcomas of the skin, neurofibromas and other tumors.

Treatment of skin leiomyoma. Surgical or laser excision, cryotherapy, intravenous or intramuscular infusions of prospidin, per course - 1-2.5 g. In case of multiple foci, a calcium antagonist - nifedipine - has a good effect.

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