Rare presentation of primary Rosai-Dorfman disease of the bone: single lesion in the proximal humerus with no clinically evident lymphadenopathy. A case report

Abstract

Introduction: Rosai-Dorfman disease (RDD) is a rare non-neoplastic histiocytic proliferative disease of non-Langerhans cells. Secondary extranodal involvement occurs in approximately 40% of cases, with bone involvement accounting for less than 10% of these cases. Primary extranodal presentation in bones (i.e., without evident lymph node involvement) is even rarer and usually multifocal, but on some occasions, it can appear as a solitary lesion.

Case presentation: A 22-year-old woman, with pain in her right shoulder without a history of trauma and refractory to pharmacological therapy, presented with functional loss of the limb after two months. X-ray and magnetic resonance scans revealed a well-defined lytic lesion in the greater tuberosity of the right humerus and surrounding bone edema extending to the proximal diaphysis, involving the rotator cuff. Given the size of the lesion (26 mm) and the suspicion of chondroblastoma, an excisional biopsy was performed. Furthermore, considering the severity of the edema, after repairing the rotator cuff, a total synovectomy was performed using a cortico-cancellous particulate allograft to correct the residual defect. Histopathological analysis showed abundant emperipolesis and positivity for CD68 and S100 biomarkers in histiocytes, leading to a diagnosis of RDD. Eleven months after surgery, the patient experienced shoulder pain and functional disability again, and clinical and imaging findings suggested tumor recurrence. Therefore, she underwent a revision surgery (resection of the lesion and local augmentation with an autologous graft). Histopathological analysis ruled out tumor recurrence and concluded that the lesion was caused by bone graft resorption. At the most recent follow-up (30 months after index surgery), the patient showed adequate functionality and mobility of the right shoulder and reported that pain was imperceptible.

Conclusions: Primary RDD of bone should be considered as a differential diagnosis when an atypical lytic bone lesion is found, particularly in a young person. Also, a timely diagnosis requires a multidisciplinary approach.