A 53-year-old woman with a four month history of chills and 60 pounds weight loss, with a recent onset of pain in the left leg with swelling and bruising two weeks before. She also complained of recent worsening of her dry cough and shortness of breath which had been present for four years.
Plain films of the distal femurs demonstrate bilateral symmetric sclerosis involving the distal diaphysis and metaphyseal region of both femurs.
CT of bilateral femurs and tibias confirmed the findings on plain film, demonstrating symmetric sclerotic lesions in the metaphyses of the distal femurs, proximal and distal tibias with sparing of the epiphyses.
A whole body bone scan demonstrates symmetric increased activity within the distal femurs and proximal and distal tibias.
MR of bilateral legs demonstrates extensive symmetric abnormal marrow signal within the distal femurs and proximal and distal tibial metaphyses. In addition, abnormal diffuse myositis involving the bilateral lower extremities is demonstrated, most pronounced within the left adductor muscles with abnormal fascial thickening and subcutaneous fat stranding.
CT of the chest demonstrates moderate-severe centrilobular and paraseptal emphysema with upper lobe predominance. Diffuse prominent interlobular septae and increased ground glass attenuation with reticulation at the bases and curvilinear regions of fibrotic/inflammatory change scattered throughout also indicates an element of fibrosis.
Core needle biopsy of left thigh soft tissue and the left femoral bone showed benign histiocytic and spindle cell infiltrate, consistent with Erdheim-Chester disease.
Erdheim-Chester disease (ECD) is a rare, idiopathic non-Langerhans cell histiocytosis with an age range of diagnosis from 7-84 years [1]. It is a multisystem disease with diffuse infiltration of organs and bones by foamy histiocytes [1]. Thus the clinical features are nonspecific and varied and patients can be misdiagnosed for many years. However, there is almost constant bone involvement manifesting most commonly as bone pain in the lower limbs and common extraosseous clinical signs are diabetes insipidus and bilateral exophthalmos [1].
Besides histology, the only specific finding in ECD is radiographic, consisting of diffuse symmetric sclerosis of the diaphyses and metaphyses of the long tubular bones of the appendicular skeleton [2]. In fact, bone scintigraphy is virtually pathognomonic, which reveals intense, diffuse and bilaterally increased osteoblastic activity at the distal ends of the long bones of the upper and/or lower limbs [3].
Other bony findings on imaging described are periostitis and partial epiphyseal involvement [4]. Published findings on MR describe extensive replacement of marrow fat with low signal intensity soft tissue masses on T1-weighted images that protrude into surrounding soft tissues in a bilaterally symmetric pattern [5]. The MR findings on our patient revealed markedly heterogeneous signal of the bone marrow of the bilateral lower extremities most pronounced within the bilateral distal femoral metaphyses as well as the bilateral proximal and distal tibial metaphyses. At these sites, there was increased signal on the T2-weighted images with decreased signal on the T1-weighted images. Additionally, there was abnormal increased signal within the musculature of the bilateral lower extremities most pronounced in the left adductor muscles, in keeping with diffuse myositis, fascial thickening and subcutaneous fat stranding/inflammatory change, likely due to systemic infiltrative disease.
Whereas skeletal involvement is the most constant finding in ECD, clinical manifestations of histiocytic infiltration in other organ systems such as the lungs may be prominent [6]. The frequency of pulmonary involvement is reported to be 15-33% and the most common findings include an interstitial process characterised by smooth interlobular septal thickening and centrilobular nodular opacities, fissural thickening, and pleural effusions [6]. Our patient demonstrated diffuse interlobular septal thickening on CT indicative of a fibrotic process on a background of moderate-severe emphysematous change.
Prominent orbital [7], breast [8] and retroperitoneal [9] involvement has also been described in the literature. Prognosis is difficult to predict, however in a series of 37 cases the average survival was 32 months with the most frequent reported causes of death being respiratory and heart failure [1]. There is no general consensus on treatment however it can include steroids, chemotherapy, radiotherapy and surgical resection.
An important differential diagnostic consideration would include Gaucher disease, a lipid storage disease due to a deficiency in glucocerebrosidase.
Erdheim-Chester disease
Based on the provided imaging examinations (including X-ray, CT, MRI, and bone scintigraphy), the following main features can be observed:
Based on the clinical presentation (fever, significant weight loss, bone pain, muscle pain, respiratory symptoms) and imaging findings, the following diagnoses or differential diagnoses are considered:
Considering the patient’s age, symptoms, weight loss, and the characteristic bilateral lower-limb bone involvement and pulmonary findings, Erdheim-Chester Disease is the primary consideration.
Combining the clinical symptoms (prolonged fever, significant weight loss, lower limb bone pain, interstitial lung changes) with the imaging findings (symmetrical sclerosis in the metaphyseal regions of long bones, bone scintigraphy showing diffuse radiotracer uptake in both lower limbs, and pulmonary interstitial disease), the overall picture strongly suggests Erdheim-Chester Disease (ECD). Definitive diagnosis typically requires histopathological confirmation (e.g., “foamy” histiocytes in bone or other involved tissues).
There is currently no standardized regimen for Erdheim-Chester Disease. Common therapeutic approaches include:
In managing Erdheim-Chester Disease, patients may experience:
Hence, an individualized rehabilitation and exercise program is needed to gradually restore functional capacity and maintain cardiopulmonary fitness:
Based on the FITT-VP principle (Frequency, Intensity, Time, Type, and Progression) when adjusting the exercise program:
This report is based solely on the current imaging and clinical information provided and cannot replace a thorough clinical evaluation or other specialized examinations. Please consult a specialist for specific treatment and rehabilitation advice.
Erdheim-Chester disease
