Rosai-Dorfman disease presenting as a solitary mediastinal mass

Our plain-English summary of Rosai-Dorfman disease presenting as a solitary mediastinal mass, by A.I. Hida, S. Yagi, Y. Obase, et al (Pathology International, 2009).

The study

• Authors: A.I. Hida, S. Yagi, Y. Obase, H. Nishimura, T. Akiyama, I. Irei, S. Hamazaki, M. Oka, Y. Sadahira
• Journal: Pathology International
• Published: 2009;59(4):265-8
• Type of article: Case report
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Rosai-Dorfman disease (RDD) involving an extranodal site is a diagnostic challenge. Reported herein is the case of a 67-year-old man who presented with a solitary superior mediastinal mass. The lesion was clinically suspected of malignancy including lymphoma because of its high uptake during a (67)Ga-scintigram and (18)F-fluorodeoxyglucose-positron emission tomography. There was no evidence of spread of the disease. Histology of thoracoscopic biopsy specimens indicated granulomatous lesion with infiltration of lymphocytes, plasma cells, and histiocytes with lymphocytes engulfed in their cytoplasm. The lesion did not contain lymph node or thymic elements. On immunohistochemistry the histiocytes were positive for S-100 protein, CD68, and CD163 but were negative for CD1a. These findings suggested a diagnosis of RDD. Despite lack of intervention, the lesion remained almost the same size for 3 years. To the best of the authors' knowledge this is the first case of RDD presenting as a solitary mediastinal mass.

In plain English

This case report from Kawasaki Medical School in Japan described a Japanese man with no symptoms whose yearly chest X-ray showed a large mass in the upper mediastinum, the central chest area between the lungs. The article gives his age as 67 in its abstract and 61 in the case description. He had been exposed to asbestos and from time to time had fluid around the lungs (pleural effusion). Scans showed the mass taking up tracer strongly, so doctors suspected cancer, including lymphoma. A first biopsy was too small to evaluate. A second biopsy, taken by thoracoscopy, showed immune cells called histiocytes that had engulfed lymphocytes. It contained no lymph node or thymus tissue. Staining of the histiocytes pointed to a diagnosis of Rosai–Dorfman disease. Iron staining found no asbestos bodies, and the article does not discuss any link between his asbestos exposure and the disease. The mass was not treated, and after 3 years it had not changed in size. The authors concluded this appeared to be the first reported case of the disease confined to the mediastinum.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report
• Who was studied: One Japanese man with no symptoms, found to have a large mediastinal mass on yearly chest X-ray screening, seen at Kawasaki Medical School, Kurashiki, Japan. His age is given as 67 in the article's abstract and 61 in the clinical summary.
• Exposure: The patient had past asbestos exposure; no fiber type, job or dose is given.
• Main results:
  • CT showed a superior mediastinal mass around the aortic arch with no pathological lymphadenopathy. Gallium scintigraphy and FDG-PET showed uptake in the mass, and malignancy including lymphoma was suspected.
  • The first biopsy, taken by mediastinoscopy, was too small to evaluate. The second, taken by thoracoscopy, showed granulomatous lesions with histiocytes that had engulfed lymphocytes. No lymph node or thymus tissue was present.
  • On immunohistochemistry the histiocytes were positive for S-100 protein, CD68 and CD163 and negative for CD1a. These findings suggested Rosai–Dorfman disease.
  • Southern blotting showed no clonal rearrangement of T-cell receptor or immunoglobulin heavy-chain genes.
  • No asbestos bodies were found in the biopsy tissue on iron staining.
  • After 3 years of follow-up without treatment, the patient was alive and the mass had not changed in size.
• The authors' conclusion: The authors concluded that this appeared to be the first reported case of Rosai–Dorfman disease confined to the mediastinum without involvement of any other site. They added that repeated biopsies can be needed to make the diagnosis.

Topics

Medical terms in this study, explained in our Lexicon: Histology, Thoracoscopic Biopsy, Immunohistochemistry, S-100.

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