AJHE2213 - CME/CMLE - Strong Co-expression of Transcription Factors PU.1 and OCT-2 in Rosai-Dorfman Disease-Strong Co-expression of Transcription Factors PU.1 and OCT-2 in Rosai-Dorfman Disease

Strong Co-expression of Transcription Factors PU.1 and OCT-2 in Rosai-Dorfman Disease

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The document discusses the findings of a study on Rosai-Dorfman disease (RDD), a rare disorder characterized by the accumulation of large histiocytes showing emperipolesis. The study aimed to investigate the expression of transcription factors PU.1 and Oct-2 in RDD histiocytes. Results showed that both PU.1 and Oct-2 were consistently expressed in RDD cases, with PU.1 providing a robust marker with crisp nuclear staining. The study included 19 RDD cases involving various sites, with PU.1 and Oct-2 being positive in all cases. PU.1 also stained engulfed inflammatory cells, while Oct-2 highlighted background plasma cells. Additionally, two patients had concurrent RDD and Langerhans cell histiocytosis, with PU.1 staining both components and Oct-2 staining only RDD histiocytes. The coexpression of PU.1 and Oct-2 proved useful in distinguishing histiocytic/dendritic cell proliferations.<br /><br />The study also explored the utility of PU.1 in diagnosing RDD when conventional markers like CD163 were variable or negative. Findings indicated that PU.1 expression can help confirm RDD diagnosis in such cases. While Oct-2 aids in distinguishing RDD from other histiocytic neoplasms, PU.1 does not serve this purpose. The document emphasizes the importance of understanding the derivation of histiocytic disorders to guide targeted therapy decisions. The differential staining patterns of PU.1 and Oct-2 provide unique diagnostic insights into RDD and its co-occurrence with other conditions like lymphomas or Langerhans cell histiocytosis. Furthermore, the document highlights the need for further research to elucidate the pathogenetic link between co-existing RDD and LCH.

Keywords

Rosai-Dorfman disease

RDD histiocytes

transcription factors

PU.1

Oct-2

histiocytic neoplasms

CD163

Langerhans cell histiocytosis

histiocytic disorders

targeted therapy