Overview.
Multicentric reticulohistiocytosis is also known as reticulohistiocytosis, giant cell histiocytoma, lipoid cutaneous arthritis, and multicentric reticulohistiocytosis of the skin and synovium. Since the basic pathological changes of this disease are granulomas and the abnormal cells are mainly histiocytes, it is currently considered a non-inflammatory granulomatous disease, which is basically characterized by single or multiple papules or nodules on the skin or mucous membranes with arthropathy, sometimes combined with systemic or local symptoms and signs, and the typical histologic image of histiocytes and multinucleated giant cell infiltration.
Etiology
The etiology of this disease is still unclear, and it was once mistakenly thought that this disease and rheumatoid arthritis were the same disease, but in fact, there are obvious clinical, pathological and serologic differences between the two diseases, so they are similar to the granulomatous allergic reaction in the process of rheumatism. In this disease, there is lipid deposition in histiocytic giant cells, which is considered to be only a degenerative process; or in response to some stimulus-induced histiocytic granulomas, the histiocytes phagocytose a variety of lipids secondary to the disease.
Symptoms.
The disease is seen in adults, predominantly in women. The earliest manifestations are skin and joint symptoms, which may occur sequentially or simultaneously.
1. Skin
All patients have skin lesions, mainly papules and nodules, which are hard and brownish-red or yellowish in color. They are commonly found on the upper limbs, forehead, neck and upper trunk. The papules are usually small and numerous, and the nodules are larger and less numerous. Papules and nodules may be mixed, and the rash varies slightly from site to site. In almost all cases, a hand and finger rash is seen, with a predominance of lateral surfaces on the extensor surfaces of the interphalangeal joints, and larger, more deeply infiltrated isolated nodules and tumor-like changes on the elbows, knees, and extensor surfaces of the forearms. The forearms were dominated by small papules, scattered or fused to form a mossy pattern. The face and trunk are dominated by small papules, sometimes resembling hairy erythema in appearance.
2. Mucous membrane
Half of the patients can be seen mucous membrane papules, with the lips and tongue most common, followed by the buccal mucosa and gingiva, the throat and cornea can also be a rash, but less common. The lips are characterized by papules and nodules of varying sizes, the tongue is predominantly papular, and the buccal mucosa is characterized by small red papules, which may sometimes be small blister-like nodules. About 1/4 of the cases can be seen yellow tumor-like rash, the number is usually large, after a certain period of time can subside, but often recur.
3. Joint lesions
Most of the cases are symmetrical polyarthritis, which can lead to joint deformity and dysfunction. It often violates the limbs, spine, temporomandibular joints and other large and small joints. The last interphalangeal joints are the most affected. When the disease is insidious, the lesions may progress asymptomatically to joint disability, especially in the hands and feet. Recurrent episodes of carpal tunnel syndrome and palmar fascial fibroproliferative hand contracture are also more common osteoarticular manifestations of the disease. Early on, redness, swelling, heat and pain are seen in the joints, sometimes with joint cavity effusion, and deformity often develops after the acute phase.
Examination
1. Laboratory examination
Half of the patients have anemia and mildly increased blood sedimentation, and a few have elevated phospholipids and triglycerides. The serum albumin to globulin ratio is mildly inverted. The test for rheumatoid factor is usually negative.
2. Other examinations
X-ray examination, in the early stage of the disease, the joint space is widened, and there is a small amount of fluid. If the disease develops further, the joint surface will be destroyed, and the joint space will be narrowed and the joint will be deformed. A few patients may have nodular or diffuse infiltrative lesions on chest X-ray.
3. Histopathology
In the dermis or even subcutaneous tissue, there are histiocytes with granulomatous proliferation, and many histiocytic multinucleated malformed giant cells are seen. The nuclei are obvious, the cytoplasm is rich, stained light red, containing uniform fine granular material, in the form of “hairy glass”, and occasionally see xanthoma giant cells and foreign body giant cells.
Diagnosis
The diagnosis of the disease is mainly based on the single or multiple papules and nodules on the skin, accompanied by symmetric polyarthritis, acute changes with redness, swelling, heat and pain in the early stage, and later bone destruction and deformity, combined with the pathology of a large number of histiocytes and giant cells of strange morphology, but without mitosis and nuclear staining, which can be diagnosed.
Differential diagnosis
This disease should be distinguished from rheumatoid arthritis, abnormal lipid metabolism, histiocytosis and malignant lymphoma. Although the joint symptoms of this disease are clinically very similar to those of rheumatoid arthritis, the latter rarely has extensive skin lesions, and the histologic changes of the two are quite different. The disease needs to be differentiated from lipid metabolism disease because of the many foam cells (hairy glass-like cells) seen pathologically and the yellow tumor rash seen clinically. Arthrogryposis with a large number of histiocytes of various morphologies and multinucleated giant cells seen pathologically is rare in metabolic diseases. The rash sometimes resembles histiocytosis X and malignant lymphoma morphologically, but is clearly differentiated pathologically, especially in the bizarre cellular morphology, but mitosis and deep nuclear staining are not evident.
Treatment.
There is no specific treatment for this disease. Glucocorticoids are helpful in controlling joint symptoms. Tretinoin is effective in improving joint symptoms but relapses after discontinuing the drug. Surgical excision or laser treatment is possible for single lesions.