The non-Langerhans cell histiocytoses (N-LCH) represent a group of rare diseases with different clinical presentations and imaging features to classical LCH. While there is a long list of entities, only few present with musculoskeletal soft tissue and osseous manifestations alongside the more commonly reported systemic findings. Erdheim-Chester disease (ECD) is typically seen in adults as bilateral and symmetrical long bone osteosclerosis. Rosai-Dorfman disease (RDD) is more commonly seen in children and young adults with bone involvement usually being a manifestation of extra-nodal disease. Primary osseous RDD is very rare, with both displaying rather non-specific imaging features of an expansile lucent lesion with or without an extra-osseous component. Juvenile xanthogranuloma (JXG) is a benign disorder typically seen in very young children. The most common imaging manifestation is a dermal or sub-dermal soft tissue mass. This article reviews the musculoskeletal imaging appearances of the commoner N-LCH.

Multicentric reticulohistiocytosis (MRH) is a rare non-Langerhans histiocytosis of unknown etiology with a predilection for joint and skin. The characteristic clinical features are papulonodular skin eruptions and inflammatory polyarthritis, sometimes progressive to arthritis mutilans, a severe destructive arthropathy. Although these manifestations can present at the same time, it is more common that one feature precedes the others. Notably, these features are similar to those found in some rheumatic diseases, such as rheumatoid arthritis or dermatomyositis, and this can lead to a misdiagnosis, especially during periods where only one feature is present. Herein, we report a female patient with polyarthralgia and subsequent skin eruptions, who was eventually diagnosed with MRH. Her symptoms seemed to resemble those of some rheumatic diseases, but several features such as affected joints and the characteristic shape of the skin lesions did not correspond to that. The histological result of infiltration of histiocytes and multinucleated giant cells in the skin ultimately facilitated the correct diagnosis. In this paper, we review MRH briefly and highlight several differential points which enable us to increase the likelihood of correctly diagnosing MRH.

Multicentric reticulohistiocytosis (MRH) and fibroblastic rheumatism (FR) are uncommon disorders with similar joint and skin manifestations. They are usually included among the non-Langerhans histiocytoses, but recent insights drive some criticism. The diagnosis is often challenging and must be confirmed by the histological typical features. If the skin manifestations are missing, the arthritic complaints may be confused with those of other rheumatic disorders. In these cases, only a careful clinical and radiological evaluation leads to the correct diagnosis. The natural course of the diseases may rapidly develop into disabling manifestations, making an aggressive treatment strongly recommendable. There is emerging evidence that anti-tumour necrosis factor-α agents and bisphosphonates are promising drugs for MRH, while a course of methotrexate and steroids seems to be the best option for FR. Finally, the clinician should be aware that in many cases MRH, but not FR, is associated with a large number of systemic manifestations and with malignancy. This eventuality must be accurately ruled out.

Multicentric reticulohistiocytosis is a rare granulomatous disease of unknown etiology, characterized by cutaneous nodules and destructive arthritis. Skin lesions can cause significant deformity, and approximately half of affected patients develop a severe disabling arthritis. The disease is often associated with malignancy; however, the paraneoplastic nature of multicentric reticulohistiocytosis is not established. The diagnosis is confirmed by the presence of oncocytic ("ground-glass") histiocytes and multinucleated giant cells on histopathology of the cutaneous nodules and the synovial membrane.

Multicentric reticulohistiocytosis (MRH) is a rare disorder with proliferating histiocytes that develop into multinucleated giant cells with "ground-glass" cytoplasm. The disease presents with a rapidly destructive, sometimes permanently debilitating, polyarthritis and a papulonodular eruption, generally of the face and hands. We present 3 cases of MRH in which the initial clinical diagnosis was thought to be dermatomyositis (DM). The cutaneous findings in these cases included an erythematous, predominantly photodistributed macular and papular eruption clinically consistent with DM. However, skin biopsy specimens revealed the diagnosis of MRH. This previously unreported clinical similarity between MRH and DM is significant because the treatment options and future complications vary greatly between the 2 diseases. Thus, it is important to consider the possibility of multicentric reticulohistiocytosis when evaluating a patient with the clinical diagnosis of dermatomyositis.

Multicentric reticulohistiocytosis (MRH) is a rare systemic disease, presenting with typical skin abnormalities and erosive polyarthritis, which is often associated with malignancy.

A case of MRH arthropathy, in which the typical nodular skin manifestation of the disease was absent, is described in a patient with a past history of breast cancer and no evidence of recurrent or new malignancy.

Careful clinical and roentgenological evaluation disclosed important clues to differentiate this condition from other more common distal interphalangeal arthritides--namely, osteoarthritis and its "erosive" variant, rheumatoid arthritis, psoriatic arthritis, tophaceous gout, dialysis related hand arthropathy, and from the rarer fibroblastic rheumatism, all of which can be mimicked by MRH. Histopathology showed the characteristic histiocytic and multinucleated giant cell infiltrate with ground glass cytoplasm, and immunohistochemical analysis showed markers evocative of a monocyte/macrophage origin of MRH.

A case of multicentric reticulohistiocytosis in an 8-year-old girl, which is a diagnosis rarely seen in children, is presented. Multicentric reticulohistiocytosis is a disorder of unknown aetiology, predominantly affecting the joints, skin and mucosa. Joint symptoms, but not cutaneous lesions, have improved with treatment with methotrexate.

Accurate diagnosis of early arthritis is important because successful treatment with preservation of joint structure and function is most likely when specific therapeutic interventions are instituted early in the disease. Early arthritis may be difficult to accurately diagnose clinically, even for experience practitioners. High-yield radiologic studies are possible, but the radiologist must realize that for each patient and each disease, how and where to look, and what to look for, may differ. Conventional radiographs remain the most important screening studies for both the axial and appendicular skeleton. Other modalities, especially MRI, have limitations but can be powerful tools in problem cases. Each disease has target areas of early involvement that may differ from the classic distribution seen once the process is established. A careful examination of these areas for subtle but characteristic early findings will often be rewarding.

Interest in the rheumatologic manifestations of cancer is related in part to practical considerations, ie, earlier cancer diagnosis is possible through enhanced awareness of cancer-associated rheumatic syndromes. The spectrum of rheumatic disorders associated with cancer includes over 30 conditions, including hypertrophic osteoarthropathy, polymyalgia rheumatica, palmar fasciitis with polyarthritis, most autoimmune connective tissue diseases, and the more recently described antiphospholipid syndrome. It is generally held that extensive search for occult malignancy in most rheumatologic disorders is not cost efficient and not recommended unless accompanied by specific findings suggestive of malignancy. The present article discusses the supplementary findings that may justify malignancy evaluation.

The case is reported of a 63 year old man presenting with a rapidly destructive symmetrical polyarthritis and widespread papular nodular skin lesions, confirmed by a biopsy to be due to multicentric reticulohistiocytosis. Biventricular cardiac failure developed secondary to extensive myocardial infiltration with multicentric reticulohistiocytosis, a complication of this disease which has not previously been reported. The joint, skin, and cardiac manifestations of multicentric reticulohistiocytosis substantially regressed following resection of an associated squamous cell carcinoma. This report adds to the small amount of published work which suggests that multicentric reticulohistiocytosis can be a paraneoplastic disease that may respond to treatment directed at the underlying tumour.

Skin disorders in which a radiograph may detect associated bony changes or abnormalities of calcification are discussed. They are grouped into eight categories: (1) inherited diseases (e.g., alkaptonuria, neurofibromatosis); (2) congenital disorders (e.g., Sturge-Weber and Proteus syndromes); (3) inflammatory conditions (e.g., dermatomyositis, sarcoidosis); (4) infections (e.g., dental sinus, syphilis); (5) neoplasias (e.g., histiocytosis, mastocytosis); (6) drug- and environment-induced (e.g., acroosteolysis, retinoid toxicity); (7) calcinosis cutis; and (8) osteoma cutis. The first part of this review, published in the August 1991 issue of this JOURNAL, dealt with the first two categories; part II discusses categories 3 through 8.

Multicentric reticulohistiocytosis is a rare multisystem disorder that reflects a reactive inflammatory response to an undetermined stimulus. While the disease is characterized as a dermatoarthritis, multiple organ systems including cardiac and skeletal muscle, the pleura and gastrointestinal tract have been involved in reported cases. The synovitis can be quite destructive with arthritis mutilans developing in a substantial percentage. The dermatitis may be particularly disfiguring when the face is involved. This chapter describes the clinical and laboratory features of the 33 cases of MRH previously reviewed by Barrow and Holubar and an additional 33 cases that have appeared in the medical literature since that report. We note an apparent decline in frequency of some manifestations of MRH. This may be due in part to the nature of the recent reports which often present a brief clinical report and focus primarily on specific disease associations, unusual manifestations, new organ system involvement or treatment regimens. The primary cell involved in the reactive inflammatory response of MRH is the phagocytic tissue histiocyte (macrophage). While uncontrolled proliferation of these reticulohistiocytes is seen in several infectious and malignant conditions there is presently no direct evidence of a particular organism or neoplasm involved in the aetiopathogenesis of MRH. There is evidence of tuberculosis exposure in one third of cases with active tuberculosis present in 5%. Likewise, malignancies are reported concomitantly with MRH in 15-28% of cases. The therapeutic trend in MRH is to treat early and aggressively to prevent the devastating arthropathy and disfiguring cutaneous sequelae. This recommendation, however, is largely based on anecdotal reports and thus the physician encountering a case of MRH needs to proceed with circumspection.

A case of multicentric reticulohistiocytosis with thyroid involvement is reported. This systemic condition has an unknown cause and is manifested by the development of nodules containing an infiltrate of characteristic histiocytic and multinucleated giant cells in the synovium, skin, subcutaneous tissues, and occasionally bone or other tissues.

A case of multicentric reticulohistiocytosis (MR) in a 24-yr-old woman is presented. MR is a rare disorder characterized by progressive polyarthropathy and a papulo-nodular skin rash. The diagnosis was established by histological examination of biopsies of erythematous nodules on the fingers which showed circumscribed collections of large mononuclear cells and multinucleate giant cells in the reticular dermis. These were embedded in a fine network of mature fibrous tissue with a scanty lymphocytic infiltrate. Histochemical, immunopathological and ultrastructural investigations confirmed that the large mononuclear cells had the properties of macrophages. The histopathological features of MR are reviewed in the light of current knowledge of macrophage physiology, and evidence for lymphocyte-histiocyte interactions in the pathogenesis of this bizarre granulomatous disorder is presented.

Multicentric reticulohistiocytosis is a histiocytic disorder affecting primarily skin and joints but occasionally involving other organ systems as well. A case is presented and the disease is reviewed, including discussion of historical, clinicopathologic, radiologic, etiologic, therapeutic, and prognostic aspects.

A family is described which has exhibited in four generations a bizarre form of arthritis mutilans and osteolysis, the features of which seem to fit most closely with a diagnosis of hereditary multicentric osteolysis, a subgroup of idiopathic multicentric osteolysis. The differential diagnosis of arthritis mutilans associated with osteolysis is discussed; this includes a wide variety of disorders ranging from rheumatoid arthritis to rare conditions such as the Winchester syndrome.