FINAL DIAGNOSIS: UNIFOCAL LANGERHANS CELL HISTIOCYTOSIS OF THE CLIVUS.
The disparate group of diseases now collectively referred to as Langerhans cell histiocytosis (LCH) include diseases previously designated histiocytosis X, eosinophilic granuloma, Letterer-Siwe disease and Hand-Sch¨šller-Christian syndrome, Hashimoto-Pritzker syndrome, self-healing histiocytosis, pure cutaneous histiocytosis, Langerhans cell granulomatosis, Type II histiocytosis, and the generic term nonlipid reticuloendotheliosis . LCH is a disease of unclear etiology characterized by neoplastic proliferation of Langerhans cells [6, 7]. LCH usually affects children and frequently involves bone structures including bones of the cranium and the skull base . However, manifestation of LCH within the clivus is extremely rare. To our knowledge this is the second report of an adult patient with unifocal LCH of the clivus . Neuroradiologically, the lesion mimicked a chordoma, chondroma or chondrosarcoma, all lesions that usually occur in adults and - except from chondroma - are more commonly located in the clivus than LCH [3, 4].
The present case differs clinically from the case previously reported by Sampson and colleagues  regarding pain type (frontal in our case vs. retro-orbital), cranial nerve involvement (inconspicuous vs. unilateral palsy of abducent nerve) and gadolinium enhancement (heterogeneous vs. homogeneous).
So far no standardized therapeutic strategy for LCH exists. Prognosis and treatment options depend essentially on the number of affected sites (unifocal or multifocal disease) and on the number of affected systems (single system or multiple systems disease). Unifocal single system disease (formerly referred as eosinophilic granuloma) has a relatively favorable prognosis with overall survival rates of more than 95% and spontaneous remission being not uncommon, although progression to multifocal disease occurs in about 10% of cases [2, 6]. In our case there was no evidence for additional osseous or extra-osseous manifestation of LCH, corresponding to unifocal osseous LCH of the clivus.
While chordomas and chondrosarcomas are usually radically resected, neurological morbidity following aggressive surgical treatment for LCH is not warranted. The optimal treatment for chordomas and chondrosarcomas of the cranial base is gross total removal associated with radiotherapy, preferentially proton beam therapy or carbon ion radiotherapy. Conservative lesion removal rather than total resection has priority in the management of LCH lesions. Therefore, pre- and intraoperative diagnosis suspicion based on radiological images and intraoperative frozen section exam have a fundamental impact on the proper management of such disease. The present case shows us that LCH of the clivus may mimic chordomas and chondrosarcomas of the skull base and should be included in the differential diagnosis of clival lesions.
To Professor Marx (National reference center for lymph node pathology, Institute of Pathology, University of Wurzburg, Germany) for confirmation of our diagnosis.
Contributed by Rudi Beschorner, Andrei Koerbel, Jens Schittenhelm, Jan Kaminsky, Hubert Loewenheim, Eva Bueltmann, Marcos Tatagiba, Richard Meyermann, Manfred Wehrmann