FINAL DIAGNOSIS: INTRACEREBRAL ROSAI-DORFMAN DISEASE
Dexamethasone was given for 40 days for reduction of the edema. Stereotaxic brachytherapy with permanent 125I seeds in a cumulative dose of 65 Gray was initiated. The radiotherapy was associated with development of significant edema, but the lesion regressed and finally disappeared. Three years after the diagnosis the child is still free of tumor.
In 1969 Rosai and Dorfman described a rare benign histiocytic disorder of unknown etiology, which they termed sinus histiocytosis with massive lymphadenopathy (SHML) 1. The disease most often affects young adults and presents with painless cervical lymphadenopathy, fever, weight loss and an elevated erythrocyte sedimentation rate. Extranodal forms of Rosai-Dorfman disease (RDD) occur in 43% of patients 2. Most common sites are skin, respiratory tract and bone. However, isolated intracranial RDD is rare with only 40 previously reported cases 3-5. The intracranial disease tends to occur in older patients (mean 39.4 years) compared to the systemic disease (mean 20.6 years) 2, 6. Only two of the reported cases presented in the first decade. The sex distribution is 1.4:1 male to female in systemic and 1.5:1 in isolated intracranial disease 2. Lesions are either solitary or multiple and well circumscribed. The tumors are mostly dural-based and in some cases associated with adjacent bone erosion. Clinical symptoms are dependent on the location of the lesion and include headaches due to mass effect, seizures, cranial nerve palsies or pituitary dysfunction 7, 8. Only a few intraparenchymal lesions have been described. These occurred in older patients and were located in the frontal or temporal lobes or the cerebellum9-11. To our knowledge, this case is the first presented of a child with an intraparenchymal lesion of the CNS. In particular, the nucleus lentiformis as location is uncommon and has not been reported previously.
By neuroimaging, RDD displays features typical of meningioma. On T2-weighted MR images, the lesions are usually hypointense or isointense and contrast-enhancing 12, 13. As the lesion can rarely be located in the brain parenchyma, like in our case, first line differential diagnoses are glioma or brain abscess.
The histopathological differential diagnoses include Langerhans cell histiocytosis (LCH), lymphoproliferative disorders, lymphoplasmacyte-rich meningioma and infection. The most characteristic feature in the histology of RDD is the presence of S100+ and CD1a-negative histiocytes, which show emperipolesis of lymphocytes, and occasionally of plasma cells or neutrophils 14. In contrast, histiocytes in LCH are CD1a+ and emperipolesis is not observed. Still, the diagnosis of RDD can sometimes be difficult, as emperipolesis may be less marked in intracranial disease 6.
The prognosis of isolated intracranial disease is usually benign, although one death has been reported occurring 5 days after subtotal resection of a falx lesion 15. Due to the rare incidence, a treatment protocol has not yet been established. In most cases, surgery or stereotaxic biopsy for diagnosis or relief of intracranial pressure is performed. The patient presented here was stereotactically biopsied for diagnostic purposes. As a surgical resection was not possible due to the peculiar location of the mass, 125I seeds were implanted stereotactically after treatment with corticosteroids for reduction of edema. The combined therapy led to complete resolution of the lesion and the patient remained free of recurrence within a three-year observation period.
Recurrence following complete surgical resection has not been described, but reports on long-term follow-up of intracranial disease are also rare 6, 16. Postoperative radiation therapy has been chosen after subtotal surgical resection 17, 18. In several cases, steroid treatment 19-21 has been employed.
In conclusion, Rosai-Dorfman disease should be considered in the differential diagnoses of both dural-based and intraparenchymal lesions of the CNS, independent of age and gender of the patient. In peculiar locations, stereotaxic biopsy can provide histological diagnosis, and a combined treatment with 125I Seeds and steroids can be effective in eradication of the lesion.
Contributed by Miletic H, Röling R, Stenzel W, Deckert M, Benz-Bohm G, Berthold F, Voges J