Ring-shaped granuloma: causes, symptoms, diagnosis, treatment

Ring-shaped granuloma is a benign, chronic idiopathic condition characterized by the presence of papules and nodules that, as a result of peripheral growth, form rings around normal or slightly atrophic skin.

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What causes the ring-shaped granuloma?

The cause of the annular granuloma is unknown. Apparently, it is polyethnic, in its development, perhaps, play the role of infection, primarily tuberculosis and rheumatism, endocrine disorders, mainly diabetes mellitus, trauma (insect bites, sunburn, etc.) and other adverse effects, including medicinal, in particular vitamin D. In the opinion of OK Shaposhnikov and I.E. Khazizova (1985), the annular granuloma is a dermatopathological sign of a disturbance in carbohydrate metabolism accompanied by microangiopathies.

Pathomorphology of the annular granuloma

In the middle part of the dermis, foci of connective tissue necrobiosis are found in the form of granular destruction, surrounded by a histiocytic infiltrate with a palisadic arrangement of histiocytes, among which are lymphocytes, plasma cells, neutrophilic granulocytes and fibroblasts. The destruction of collagen fibers can be complete in the form of one or more areas of necrosis or incomplete in the form of several very small foci. Foci of incomplete destruction are usually small, some bundles of collagen fibers in them look normal, others in a state of varying degrees of destruction acquire a basophilic color, resembling the areas of mucoid swelling. In the infiltrate - lymphoid cells, histiocytes and fibroblasts. In the lesions, collagen fibers are located in different directions, the mucinous material has the appearance of thin filaments and granules metachromatically colored toluidine blue. Sometimes you can see single giant cells. Some authors consider pathognomonic for this disease the presence in the infiltrate of eosinophils.

A ring-shaped granuloma with very small foci of incomplete destruction of collagen fibers and insignificant infiltration around may not be noticed due to the vagueness of the histological picture, but the diagnosis can be made on the basis of the presence of histiocytes among the collagen beams and the wrong arrangement of the latter.

The epidermis is mostly without significant changes, except for cases of superficial location of necrosis, when the epidermis is exposed to ulceration (perforating form). Infiltrate in these cases is weak, consists of lymphocytes and is located perivascularly around the focus of necrosis; giant cells are rare. When mucicarmine and alcian blue are colored, mucin is detected, lipid deposition is observed in old foci. Staining for lysozyme and inhibitor metalloproteinases-1 gives a characteristic distribution of a positive reaction, which differs from other types of necrobiotic granulomas, which allows a differential diagnosis, including lipoid necrobiosis.

Electron microscopy in the necrobiosis zone reveals the remains of collagen fibers, cell debris, fibrin, amorphous granular material; in the transition zone - granular destruction of collagen fibrils, thin threads of glycosaminoglycans and infiltrate cells; in the infiltration zone - histiocytes, epithelioid cells, fibroblasts and tissue basophils with large granules.

Subcutaneous nodes (deep form) of the annular granuloma are characterized by the presence of large foci of complete destruction of collagen with palisadically located histiocytes around them. Areas of destruction are usually colored pale, homogeneous, infiltrated by fibrinous masses, surrounded by a significantly pronounced chronic infiltrate, consisting primarily of lymphocytes.

The histogenesis of the granuloma is annular. Immunofluorescence microscopy revealed deposits of IgM and C3 complement components in the walls of small vessels of the focus, partly also in the dermo-epidermal junction with fibrinogen, and in the necrotic focus together with fibrin. It is suggested that changes in the tissue at first can be similar to those in the Arthus phenomenon, and then delayed type hypersensitivity leads to the formation of granuloma. Immunomorphological examination revealed infiltrates of activated T-lymphocytes, mainly having helper / inducer phenotype, and CD1-positive dendritic cells similar to Langerhans cells, they probably play a role in the pathogenesis of the disease. It is believed that the localized and disseminated forms of the disease have a different genesis. The second form often reveals HLA-BW35. Its association with antibodies against thyroid globulin was found. Family cases are described.

Symptoms of an annular granuloma

Erythematous lesions of a yellowish, bluish color most often occur on the back of the feet, legs, hands and fingers, usually have an asymptomatic character. Ring-shaped granuloma is not associated with systemic diseases, except that the frequency of violations of sugar metabolism is higher in adults with multiple rashes. In some cases, the causes of the disease are exposure to sunlight, insect bites, skin tests for tuberculosis, trauma and viral infections.

Clinically, the typical form of the disease manifests itself as a monomorphous rash consisting of small, slightly shiny, painless nodules of a reddish or pinkish color, sometimes the color of normal skin grouped in the form of rings and semimers with preferred localization at the rear of the hands and feet. Eruptions are usually not accompanied by subjective sensations and, as a rule, do not ulcerate. The central part of the foci is somewhat sunken, cyanotic, looks slightly atrophic, more pigmented than the peripheral zone, in which separate closely located nodules are revealed. Less common are other variants: disseminated annular granuloma developing in persons with a disruption of carbohydrate metabolism, characterized by the precipitation of a large number of papules located separately or merging, but rarely forming rings; Perforating form with lesions of the skin of the distal parts of the limbs, especially on the hands, less often - the face, neck, trunk. It is possible to form scars on the site of regressed elements.

Deep (subcutaneous) form, generalized or localized, resembles rheumatic nodules, develops almost exclusively in childhood, nodes appear in the subcutaneous tissue, more often on the legs, as well as on the scalp, palms. In rare cases, adults have single ring-shaped foci on their face, mostly on the forehead skin. There are also other atypical variants (erythematous, tuberous, follicular, lichenoid, actinic). A typical form of the ring-shaped granuloma occurs mainly in children, more often in girls. In most cases, the annular granuloma regresses, although relapses are possible.

Treatment of an annular granuloma

Ring-shaped granuloma is usually not required in treatment, rashes are spontaneous, but local topical use of glucocorticoids with occlusive dressings is possible, as well as administration of glucocorticoids into foci. PUVA is effective in patients with advanced forms of the disease.