Facial Cutaneous Rosai-Dorfman Disease Mimicking Sporotrichosis: A Case Report and Discussion
Xinhuan Wang, et al.
Introduction:
Cutaneous Rosai-Dorfman disease (CRDD) is a rare form of non-Langerhans cell histiocytosis. Due to its unclear etiology and pathogenesis, and highly variable cutaneous manifestations, no definitive diagnostic criteria have been established. This leads to a high risk of diagnostic errors and missed diagnoses in clinical practice. This report describes a 64-year-old woman with facial CRDD that was initially misdiagnosed as sporotrichosis. This case highlights the importance of careful differential diagnosis to avoid misdiagnosis and ensure appropriate treatment.
Case Report:
A 64-year-old woman presented with a solitary erythematous nodule on the right cheek that had developed four months earlier without an identifiable precipitating factor. The nodule gradually enlarged, forming an erythematous plaque that ulcerated and developed a thick, greasy, yellowish-white crust. It was asymptomatic, with no associated pain or pruritus. Histopathological examination revealed epidermal pseudoepitheliomatous hyperplasia and granulomatous inflammation in the dermis, with dense inflammatory infiltrates composed predominantly of lymphocytes, histiocytes, and neutrophils. Both Periodic acid-Schiff (PAS) and acid-fast stains were negative. However, sporotrichosis remained in the differential diagnosis because the patient resided in northern China, an area highly endemic for the disease.
Based on the presence of a progressively enlarging, ulcerated, crusted erythematous plaque and the corresponding histopathological findings of epidermal pseudoepitheliomatous hyperplasia accompanied by granulomatous inflammation, sporotrichosis was established as the initial diagnosis, and empirical antifungal therapy with itraconazole (200 mg/day) was initiated. However, after two months of treatment, the lesion continued to enlarge and protrude above the skin surface. Re-examination of the original biopsy specimens, including additional sectioning and staining, revealed diffuse dermal infiltration with numerous histiocytes, lymphocytes, neutrophils, and some plasma cells. Characteristic emperipolesis was also observed. At immunohistochemical analysis, the large histiocytes were positive for CD68 and S100 but negative for CD1a and CD207. The diagnosis of CRDD was established based on these findings.
The patient subsequently underwent complete surgical excision of the lesion and was monitored for two months postoperatively, during which no recurrence was observed.
Discussion:
CRDD, first described by Rosai and Dorfman in 1969, is a rare form of sinus histiocytosis with massive lymphadenopathy. It is characterized by the accumulation of histiocytes within lymph node sinuses and various extranodal tissues. The disease most commonly affects the skin and lymph nodes. CRDD is a distinct subtype characterized by lesions confined to the skin without systemic manifestations and accounting for approximately 3% of all RDD cases.
The etiology and pathogenesis of CRDD remain incompletely understood. Evidence of clonal proliferation in some cases suggests a potential neoplastic component. Other studies have proposed associations with immune dysregulation, infectious agents, and genetic factors. CRDD may occur as an isolated condition or in conjunction with autoimmune disorders and malignancies.
CRDD can develop at any age, with a mean onset of approximately 45 years, and exhibits a slight female predominance. Its clinical manifestations are remarkably diverse, presenting as papules, nodules, plaques, or other morphologic variants. Typical lesions are firm, reddish-yellow papules or nodules that may show surface scaling and, occasionally, tenderness.
Diagnosis relies primarily on histopathologic evaluation, which typically reveals a dense dermal infiltrate consisting of histiocytes, lymphocytes, plasma cells, and neutrophils. The hallmark histological feature is emperipolesis: the engulfment of intact inflammatory cells within histiocytes. However, emperipolesis is not universally observed and might only be detected through serial sectioning and meticulous microscopic examination, making diagnosis occasionally challenging.
In the present case, the cutaneous nodule initially observed on the patient’s face closely resembled sporotrichosis. However, over the course of several months, the lesion grew rapidly into a large, tumor-like mass several centimeters in diameter. Failure of the initial histopathologic examination to detect emperipolesis probably contributed to the incorrect preliminary diagnosis and the inappropriate prescription of antifungal therapy. Only after subsequent resection and deeper sectioning of the tissue were more characteristic histopathologic features of CRDD detected, after which the diagnosis was further confirmed by comprehensive immunohistochemical analysis.
Conclusion:
In clinical practice, when CRDD is suspected, thorough evaluation is essential to ensure diagnostic accuracy and appropriate management. A detailed medical history, assessment for potential comorbidities, and prompt histopathologic and immunohistochemical examinations are critical for establishing the correct diagnosis. Additionally, fungal culture is critical when fungal infection is included in the differential diagnosis. Such vigilance helps prevent misdiagnosis or delayed recognition, thereby avoiding inappropriate treatment and potential disease progression.
