60‐YEAR OLD WOMAN WITH EXTRA‐AXIAL FRONTAL MASS

CLINICAL HISTORY

A 60‐year old woman with past medical history of diabetes, systemic hypertension and diminished visual acuity since early infancy presented with progressive visual loss of the left eye occurring over 24 months prior to consultation. Physical examination revealed a blind left eye with atrophy of the optic papilla. No lymphadenopathies, fever, or weight loss were detected. On magnetic resonance imaging (MRI), an extra‐axial mass, hypointense on T2‐weighted scans, hyperintense on T1‐weighted scans, with contrast enhancement along the posterior aspect of the left optic nerve cranial entrance, measuring 1.8 × 3 cm (Figure 1) was visualized. A left frontotemporal craniotomy was performed and a pink‐yellow soft mass was resected in its entirety. No evidence of brain invasion or involvement was found. Even though a preoperative MRI angiography (to rule out a potential aneurysm) was negative, the lesion bled during the procedure, and an intraoperative digital angiogram was done which was also negative for aneurysm.

Figure 1.

GROSS AND MICROSCOPIC PATHOLOGY

Macroscopically, the surgical specimen tissue was whitish‐yellow, lobulated, elastic, and measured 2.5 cm in diameter. Intraoperative pathology examination revealed monomorphic cells distributed in sheets or clusters interspersed with eosinophils, lymphocytes and occasional neutrophils, with cells that had histiocytic characteristics imparted by clear cytoplasm and prominent nuclei and nucleoli. Based on the lesion histology, an intraoperative diagnosis of “histiocytic lesion, not otherwise specified” was reached. Permanent sections showed xanthomatous histiocytes with large nuclei displaying prominent nucleoli distributed in small lobules or sheets. Occasional xanthomatous cells displayed multinucleation; however, typical Touton giant cells were not visible. The inflammatory component was composed of lymphocytes, plasmocytes, neutrophils and eosinophils (Figure 2). Tumor cells were immunoreactive for CD68 (Figure 3, occasionally for S100 (Figure 4), but not for CD1a (not shown).

Figure 2.

Figure 3.

Figure 4.

DIAGNOSIS

Non‐Langerhans cell histiocytosis corresponding to Erdheim‐Chester Disease (ECD). Follow‐up MRI displayed no evidence of tumor recurrence.

DISCUSSION

Erdheim‐Chester Disease (ECD) is a member of the group of diseases known as Histiocytosis, encompassing a broad spectrum of mainly systemic diseases (bone and visceral) whose features depend mainly on the presence or absence of dendritic Langerhans cells. ECD lacks systemic symptoms (as does Rosai‐Dorfman disease [RDD]) and can present as a tumor‐like mass in the central nervous system (CNS). (7) Systemic 11,1), skeletal 4, 6, 10 or extraskeletal involvement,5, 9 may be present. More rarely the disease is initially diagnosed as a solitary mass in the CNS (12). In terms of the histological assessment, this case showed typical features as described in other reports. 12, 10) However, two issues merit further discussion: first, although occasional multinucleated cells were observed, no typical Touton giant cells were detected as previously reported by other authors.12, 11, 2) This is in agreement with other series describing complete absence of Touton giant cells (8), or the presence in some cases of only a single cell (6). Second, although the lesion was CD68 positive and CD1a negative, i.e. presented the expected immunophenotype 8, 2, 12, 1); occasional cells were S100 positive, demonstrating once again the controversy surrounding use of this immunostain for histiocytosis characterization.(6) In most reports S100 was negative,2, 11, 12 however, a few articles have been published in which it was weakly or occasionally positive.1, 10, 13. With reference to differential diagnoses, two important neoplastic proliferations must be considered: Langerhans Cell Histiocytosis (LCH) and Rosai‐Dorfman Disease (RDD); even though the former can also present as a solitary CNS mass (3), it usually shows different immunophenotype from ECD (namely CD1a+, S100‐ and CD68‐); the latter shows strong CD68 and S100 positivity, can clinically affect the CNS but usually presents with lymphadenopathy, fever and hypergammaglobulinemia,(12) and although isolated intracranial cases without systemic involvement have been also reported, the lack of emperipolesis in our case, as well as the absence of common clinical features such as lymphadenopathy or fever, and the presence of only isolated positive S100 cells allowed us to rule out RDD.

ABSTRACT

We describe a 60 year‐old woman presenting with visual loss of her left eye. No lymphadenopathies, fever, or weight loss were detected. Neuroimaging studies revealed an extra‐axial mass along the posterior aspect of the left optic nerve. The mass was resected and showed xanthomatous histiocytes that were positive for CD‐68, occasionally positive for S‐100, and negative for CD‐1. The lesion was diagnosed as Erdheim‐Chester disease (ECD) affecting the CNS. The patient is under systemic evaluation in order to discover other ECD lesions. Microscopic findings and differential diagnoses are discussed.