8‐YEAR‐OLD CHILD WITH A LESION IN THE LEFT NUCLEUS LENTIFORMIS

CLINICAL HISTORY

An 8‐year‐old child presented with symptoms of raised intracranial pressure starting a few days before clinical presentation. Past medical history was significant for diabetes insipidus centralis, which was diagnosed in February 2001 and treated with Minirin^®. Neurological examination was normal.

The magnetic resonance imaging scans showed a 25 mm space‐occupying lesion with distinct contrast enhancement (Figure 1). The tumor was localized in the left insular region and attached to the nucleus lentiformis and the left thalamic area. The T2 sequence demonstrated significant peritumoral edema with compression of the left ventricle and midline shift (Figure 2). A primary brain neoplasm or an abscess were considered in the differential diagnoses. A stereotaxic biopsy was performed.

Figure 1.

Figure 2.

HISTOPATHOLOGY

Histology showed a highly cellular lesion with a polymorphous mixed inflammatory infiltrate (Figure 3) consisting of histiocytes, mature lymphocytes, plasma cells and eosinophilic granulocytes (Figure 4). The histiocytes had round to oval, polymorphic nuclei and eosinophilic cytoplasm with indistinct margins, but a subpopulation had well‐defined borders. The histiocytes occasionally showed engulfed lymphocytes and plasma cells, a process referred to as emperipolesis (Figure 5).

Figure 3.

Figure 4.

Figure 5.

Immunohistochemistry revealed S100+ (Figure 6), Vimentin+ and CD68+ histiocytes, whereas staining for the CD1a receptor was negative (Figure 7). Glial fibrillary acidic protein immunostain detected reactive astrocytes. The inflammatory infiltrate consisted of CD45+ and CD3+ lymphocytes, CD138 + plasma cells and CD20 + B cells.

Figure 6.

Figure 7.

FINAL DIAGNOSIS

Intracerebral Rosai–Dorfman disease (RDD).

TREATMENT

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.

DISCUSSION

In 1969 Rosai and Dorfman described a rare benign histiocytic disorder of unknown etiology, which they termed sinus histiocytosis with massive lymphadenopathy (10). 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 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 (5). The intracranial disease tends to occur in older patients (mean 39.4 years) compared with the systemic disease (mean 20.6 years) 2, 4. Only two of the reported cases were 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 caused by mass effect, seizures, cranial nerve palsies or pituitary dysfunction (12). Only a few intraparenchymal lesions have been described. These occurred in older patients and were located in the frontal or temporal lobes or the cerebellum (6). To our knowledge, this case is the first reported of a child with an intraparenchymal lesion of the central nervous system (CNS). In particular, the nucleus lentiformis as a location is uncommon and has not been previously reported.

By neuroimaging, RDD displays features typical of meningioma. On T2‐weighted magnetic resonance images, the lesions are usually hypointense or isointense and contrast‐enhancing 8, 11. 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 meningeoma 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 plasma cells or neutrophils. 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 (4).

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 (1). Because of 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 purpose. As a surgical resection was not possible because of 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 3‐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 4, 9. Postoperative radiation therapy has been chosen after subtotal surgical resection (7). In several cases, steroid treatment (3) has been used.

In conclusion, RDD 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.

ABSTRACT

An 8‐year‐old child with a past medical history of diabetes insipidus centralis presented with symptoms of raised intracranial pressure, starting a few days before clinical presentation. The clinical examination was completely unremarkable. Magnetic resonance imaging scans showed a contrast‐enhancing lesion in the left nucleus lentiformis. Histopathologic examination revealed a highly cellular lesion with a polymorphous mixed inflammatory infiltrate consisting of histiocytes, mature lymphocytes, plasma cells and eosinophilic granulocytes. S100+ and CD1a‐negative histiocytes showed phagocytosis of lymphocytes (emperipolesis). The final diagnosis was intracerebral Rosai–Dorfman disease (RDD). Combined treatment with steroids and stereotaxic implantation of Jod‐Seeds resulted in complete resolution of the lesion within a 3‐year observation period. RDD is a benign histiocytic disorder of unknown etiology and manifests with lymphadenopathy and extranodal forms of disease involving skin, respiratory tract and bone as most common sites. However, intracranial and in particular intracerebral manifestation of RDD is a rare event. In this case histopathological features, differential diagnoses and treatment options of intracranial RDD are discussed.