MON-106 - Rosai Dorfman Presenting as Pituitary Cyst - A Case Report

Introduction: Rosai-Dorfman-Destombes disease (RDD) is a rare, non-neoplastic, multisystemic histiocytic, characterized by histiocytic proliferation within the sinusoids of lymph nodes, leading to massive lymphadenopathy.
Diagnosis is based on histopathologic features, with characteristic lesional histiocytes that are S100-positive, CD68-positive, CD1a-negative, and frequently exhibit emperipolesis. Central nervous system involvement occurs in fewer than 5% of cases. To date, fewer than 300 cases of neurologic involvement in RDD have been reported and none presenting as a pituitary cyst.

Case presentation: A 26-year-old male with a medical history of hypogonadism presented with symptoms suggestive of diabetes insipidus. Further evaluation revealed a pituitary mass, and he was started on outpatient desmopressin (DDAVP), which led to symptomatic improvement. The patient was referred for ongoing neurosurgery evaluation.
Imaging studies demonstrated a predominantly peripherally calcified cystic sellar mass involving the pituitary gland, most consistent with either a peripherally calcified Rathke's cleft cyst or an adamantinomatous craniopharyngioma. The patient was scheduled for elective surgical resection. Intraoperatively, the cyst contents, described as “concretions,” were progressively removed. No obvious fluid component was identified within the cyst, and specimens were sent for permanent pathology.
His postoperative course was uncomplicated, with no evidence of cerebrospinal fluid leak. He was started on DDAVP nightly and deemed medically stable for discharge.
Final pathology of the sellar mass resection showed mixed infiltration of histiocytes and lymphoplasmacytic cells; positive for S100 and negative for CD1a. These findings were consistent with Rosai–Dorfman disease.
Postoperative lab results were notable for elevated IgG4 levels, at 160 (normal range: 1-123), along with slightly elevated ESR and CRP.


Discussion: Intracranial RDD most commonly appears radiographically as a solitary, extra-axial, homogeneously enhancing dural-based mass, which typically resembles a meningioma. To date, there are no documented cases of RDD presenting as a pituitary cyst, making this case particularly unusual. Some studies suggest that surgical resection is effective for isolated intracranial RDD.

Given the clinical overlap between RDD and IgG4-related disease, some authors propose that, although the two conditions are pathologically distinct, they may exist along a related immunologic spectrum. This suggests the importance of excluding these pathologies before making a definitive diagnosis.

Based on our findings, it is crucial to broaden the differential diagnosis. A pituitary cyst on imaging, although rare, may represent Rosai-Dorfman disease and should be considered in appropriate clinical contexts.

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