Syringoma

Syringoma (syn: multiple syringoadenoma, eruptive hydra-cone) is a developmental defect of the eccrine sweat gland, similar in structure to the protocol department in the upper part of the dermis. 

Epidemiology

The frequency of syringoma in patients with Down syndrome is 30 times higher than in the population of patients with other mental illnesses. Syringoma is an integral part of the syndrome of Nicolau-Balus (eruptive syringoma, miliary cysts and vermicular atrophodermia). Syringoma is often combined with benign tumors or malformations of the skin. 

[1], [2], [3], [4], [5], [6]

Pathogenesis

In the superficial and middle parts of the dermis there is a large number of small and medium sized cysts of round or oval shape lined with two layers of epithelial cells. The layer of cells adjacent to the basal membrane is flattened, their cores are intensely colored; layer, facing the cavity of the cyst, consists of lighter cubical walking prismatic cells. The contents of the cysts are homogeneous or slightly granular.

In addition to cysts, there are thin strands of small cells with dark nuclei in the syringome. Some of the strands on one of the poles are cystically dilated, resembling the shape of the tadpoles, which is typical of this tumor. Cysts lined with multilayered flat epithelium and filled with layered masses of keratin can be observed. These cysts are sometimes torn, their contents fall into the dermis, causing a giant cell reaction, and, then, is calcified. Sometimes in the cysts of the syringoma marked proliferation of lining cells with the formation of solid strands, germinating the basement membrane - syringocystadenoma. The stroma of the tumor is mostly unchanged, but sometimes lymphohistiocytic infiltrates are found in it. In addition to the usual variant of the histological structure, a clear cell version of the syringoma is described.

Histochemical research reveals the activity of enzymes, characteristic of eccrine glands, succinate dehydrogenase, phosphorylase and leucine aminopeptidase, while lysosomal enzymes characteristic of apocrine structures (acid phosphatase and beta-glucuronidase) are very poorly detected. The bright cell variant of syringoma is characterized by a high content of glycogen. With electron microscopy in cells lining the tubular structures, visible microvilli, quite a lot of lysosomes and tonofilaments.

Histogenesis of the Syringoma

There are different views on the histogenesis of the syringoma. Some authors on the basis of histochemical and electron microscopic data believe that this tumor has an eccrine differentiation, while localization in places of accumulation of apocrine glands, precipitation of elements predominantly in the pubertal period and histotopic association with immature hair follicles and sebaceous glands do not exclude apocrine genesis in some cases

[7], [8], [9], [10]

Symptoms of the syringoms

The tumor is often multiple, symmetrically located on the face, especially in the eyelids, on the chest, rarely in other places. It develops more often in women in the puberty period, family cases are described. In addition, a limited localization of the syringoma on the vulva, penis, proximal hand phalanges is described. Syringoma, localized on the scalp, may be accompanied by diffuse alopecia.

A multiple version of the syringoma is a small nodule, slightly protruding above the surface of the skin, slightly shiny, as it were translucent or yellowish.

Differential diagnosis

Differential diagnosis of the syringoma is quite simple and is based on the presence of many small cysts and duct structures like "tadpoles."

[11], [12], [13], [14]