Multicentric reticulohistiocytosis with prominent skin lesions and arthritis: A case report

Table 3 The clinical characteristics of multicentric reticulohistiocytosis

Clinical manifestation
Skin lesions	The skin is the most frequently involved site of MRH. Skin lesions may be the first symptom and are primarily distributed on the face, scalp, behind the ears, neck, anterior chest, back, waist, and abdomen, arms, hands, and thigh. The manifestations of skin lesions include papular nodules, and macules. MRH can also involve mucous membranes (e.g., oral mucosa, gingival mucosa, and laryngeal mucosa)
MRH-associated arthritis	Arthritis can appear as the first symptom of MRH and also can occur simultaneously with skin lesions. MRH-associated arthritis can be characterized as diffuse, symmetric, progressive, and destructive. MRH is most commonly involved in the hand joints, especially the distal interphalangeal joint, followed by the knee joint, the shoulder, elbow, hip, ankle, and metatarsophalangeal joint. The affected joints exhibit swelling, pain, increase in skin temperature, joint effusion, and some patients can also experience morning stiffness
Other clinical manifestations	Muscle involvement: Myalgia or decreased muscle strength; Electromyography (EMG) may exhibit myogenic lesions in some patients; Lung involvement: Dyspnea, pulmonary nodules, pleural effusion, or pulmonary interstitial fibrosis; Heart involvement: Pericardial effusion and myocarditis; Laryngeal involvement: Hoarseness, foreign body sensation in the larynx, or laryngeal abnormalities; Thyroid involvement: Hypothyroidism; Thrombosis has also been reported in patients with MRH. A small number of patients have extensive systemic involvement of the larynx, lungs, spleen, and plasma membranes at the same time. Systemic symptoms: Fatigue, fever, and weight loss
Laboratory tests
Non-specific. Some patients may have increased leukocytes, decreased hemoglobin, accelerated sedimentation, and elevated lipids
Histopathology
Histopathological manifestations: a large number of histiocytes and multinucleated giant cells with an eosinophilic cytoplasm and hairy glass-like changes
Immunohistochemistry: macrophage marker CD68 is positive; the Langerhans cell tissue markers S-100, CD1a and B cell markers CD19 and CD20 are negative; CD45, CD43, Mac387, and lysozyme are positive to varying degrees
MRH-associated diseases
Systemic autoimmune diseases: systemic lupus erythematosus, rheumatoid arthritis, Sjogren's syndrome, dermatomyositis, hypothyroidism, diabetes, and tuberculosis
Malignancy: Covering almost all solid tumors and hematologic malignant diseases
Differential diagnosis
MRH is most easily confused with rheumatoid arthritis, dermatomyositis, and psoriatic arthritis
Treatment
Initial treatment: Glucocorticoids combined with immunosuppressants regimens. Commonly used immunosuppressants include methotrexate, cyclophosphamide, hydroxychloroquine, and leflunomide
Biological agents: TNF-α antagonists (e.g., etanercept, adalimumab, and infliximab), IL-6 receptor antagonists (tocilizumab), and IL-1 receptor antagonists (anakinra)
Prognosis
The prognosis of MRH patients varies greatly among individuals; It is related to treatment choice, response to drug therapy, and comorbidities

MRH: Multicentric reticulohistiocytosis; TNF-α: Tumor necrosis factor-α; IL: Interleukin.