Objective: To investigate the clinicopathologic features, diagnosis and differential diagnosis of extranodal Rosai-Dorfman disease(RDD)of the breast.
Methods: Twelve cases of extranodal RDD of the breast were analyzed using hematoxylin-eosin stain and immunohistochemical staining.The morphological features and immunophenotype were observed by light microscopy, accompanied with a review of the literature.
Results: Twelve cases of extranodal RDD of the breast are presented. The patients were women and their ages ranged from 15 to 55 years (mean =37 years). Except one patient with involvement of the right breast and ipsilateral axillary lymph nodes, other eleven patients' disease confined to the breast. Seven cases located in the right breast, the other five cases in the left breast. Microscopically, it showed a typical morphology, characterized by diffuse infiltration of large histiocytes, lymphocytes and plasmocytes that formed irregular nodular structure with light and dark appearance under microscope. Spindling of histiocytosis often arranged in a vague storiform with prominent fibrosis, accumulation of foamy histiocytes and scattered atypical nuclei. The characteristic histocytes and emperipolesis could not be seen obviously in extranodal RDD of the breast.Immunohistochemical staining showed histocytes were strongly positive for S-100 protein, CD68 and CD163, while negative for CD1a.
Conclusions: Extranodal RDD of the breast is very rare. Because of unconspicuous emperipolesis and lack of specificity in clinic and images, extranodal RDD of the breast is easy to be misdiagnosed as other histiocytosis. The microscopic differential diagnosis includes idiopathic granulomatous mastitis, infective granulomas, langerhans cell histiocytosis, IgG4 related sclerosing disease, Erdheim-Chester disease, benign fibrous histiocytoma, malignant fibrous histiocytoma and Hodgkin Lymphoma. Light and dark appearance under microscope is the important clue in diagnosis of extranodal RDD in breast. Immunohistochemistry is also helpful.