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12 February 2020 - Case of the Month #488

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Thanks to Dr. Brian McMillen, Southcoast Health Pathology Services, University Pathologists/Aurora Diagnostics (USA), for contributing this case and Dr. John DeWitt, University of Vermont Medical Center, Burlington, Vermont (USA), for writing the discussion.


INDIANAPOLIS, INDIANA (USA). The Department of Pathology and Laboratory Medicine at Indiana University School of Medicine seeks a dermatopathologist from either a pathology or dermatology background with strong diagnostic skills and an interest in teaching to join its dermatopathology division. The division serves seven hospitals, including Methodist Hospital, University Hospital, Riley Hospital for Children at Indiana University Health, IU Health West Medical Center, IU Health North Medical Center, IU Health Arnett, and Eskenazi Hospital. Consults cases from across the state and cases from community dermatologists and other providers are also part of the case mix. The department occupies a free-standing core reference laboratory building with world-class facilities.

The dermatopathology division is currently comprised of three experienced dermatopathologists, and this position represents an expansion of faculty due to growth in case volume. Excellent teaching and communication skills are essential since the division houses a dermatopathology fellowship program that has been in place for over 20 years and is accredited for two fellows. Additionally, the division teaches medical students, pathology residents, dermatology residents and participates in multidisciplinary tumor boards and grand rounds. There is strong departmental support for translational research activities and excellent collaborations exist with the Dermatology, Oncology, and Surgery Departments.

The applicant must either be Board certified or Board eligible for sub-specialty certification in dermatopathology; candidates must have a primary Board certification in pathology or dermatology. The possibility for a joint appointment in the Department of Dermatology could be pursued. Academic rank will be determined by qualifications and level of experience.

Indiana University is the sole medical school in the state of Indiana. Indianapolis is a thriving Midwestern city with a vibrant downtown community, outstanding cultural and sports facilities, beautiful suburbs and a low cost of living.

To Apply:

For questions, contact:
John N. Eble, M.D., M.B.A.
Nordschow Professor and Chairman
Dermatopathology Search
Department of Pathology and Laboratory Medicine

Indiana University is an Affirmative Action/Equal Opportunity Employer, M/F/D/V


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Case of the Month #488

Clinical history:
A 32 year old woman initially presented with right hand and wrist weakness and a left parasagittal mass on MRI suggestive of meningioma. It was excised but two years later, she presented with symptoms of an enlarging mass, and the tumor was resected again. The images are from the second resection.

Histopathology images:

What is your diagnosis?

Click here for diagnosis, test question and discussion:

Diagnosis: CNS presentation of extranodal Rosai-Dorfman disease

Test question (answer at the end):
In distinguishing extranodal Rosai-Dorfman disease (RDD) from other histiocytoses, what is the correct immunophenotype for RDD?

A. S100-, CD1a-
B. S100+, CD1a+
C. S100+, CD1a-
D. S100-, CD1a+

This is a case of extranodal Rosai-Dorfman disease (RDD) arising in the CNS. Rosai-Dorfman disease is a lymphohistiocytosis consisting of a mixed inflammatory infiltrate, variable fibrosis and typically characteristic emperipolesis (histiocytic engulfment of lymphocytes, plasma cells, neutrophils and eosinophils). RDD most commonly arises in the lymph nodes where it causes massive lymphadenopathy and sinus histiocytosis, although extranodal examples do occur, as in this case. In general, RDD shows an average age of presentation of 21 years with a slight male predominance, while in a review of the literature, the average age of presentation of CNS RDD was 41 years, with a 3.5:1 male to female predominance (J Res Med Sci 2012;17:304). The etiology of RDD is unknown, although viruses and immune dysfunction have been suggested (Hematology Am Soc Hematol Educ Program 2004:283).

Patients with CNS RDD often present with symptoms of mass effect such as headache, nausea and vomiting, as well as dizziness, fatigue, seizure, weight loss, night sweats or more distinct localizing neurologic signs (Childs Nerv Syst 2015;31:317). Cases occurring in the sellar region may cause symptoms of hypopituitarism or diabetes insipidus. Unlike in the typical nodal disease, extranodal RDD of the CNS shows the classic signs of cervical lymphadenopathy, fever and weight loss in only 30% of cases, while 52% have no associated systemic disease (J Clin Neurosci 2005;12:656).

CNS cases most often present as a dural based mass or multiple masses, commonly confused with meningioma clinically and radiologically (Childs Nerv Syst 2015;31:317), as in this case. In addition, less commonly, intraparenchymal or intrasellar localization has been observed. Grossly, they are typically dural based, with a yellow to grayish-white appearance, firm and vaguely lobulated, resembling meningioma.

Microscopically RDD consists of a mixed inflammatory infiltrate of plasma cells, prominent pale histiocytes, lymphocytes and variable fibrosis. Emperipolesis with histiocytic engulfment of intact inflammatory cells is typical, although it may not be conspicuous with routine H&E staining, can be seen in other conditions and should not be considered pathognomonic. Immunohistochemistry in RDD shows histiocytes are positive for CD11c, CD68, S100 and negative for langerin and CD1a. No genetic aberrations are known to occur in RDD and the inflammatory infiltrate has shown polyclonality in two studies (Br J Haematol 1995;91:415).

Clinically and radiologically, due to similarities in presentation, the differential diagnosis will often include meningioma. Microscopically, other histiocytic disorders may be considered, such as Langerhans cell histiocytosis (CD1a+) or Erdheim-Chester disease (S100-).

After the second resection, a subsequent MRI showed no residual disease, and the patient was asymptomatic. Annual follow up examinations are planned.

Test question answer:
S100+, CD1a-

Extranodal Rosai-Dorfman disease forms lymphohistiocytic masses with prominent pale S100+, CD1a- histiocytes. Answer A (S100-, CD1a-) is the staining pattern of histiocytes in Erdheim-Chester disease. Answer B (S100+, CD1a+) is the staining pattern of histiocytes in Langerhans cell histiocytosis.

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