[Report of a rare case of Langerhans-cell histiocytosis of the skull base].

INTRODUCTION: Langerhans cell histiocytosis, once called histiocytosis X, is a rare disease. Usually it can occur in children and is characterized by granulomas (eosinophilic granuloma and Hand-Schueller-Christian disease) or by a extensive involvement of various organs (Letterer-Siwe disease). The etiology remains uncertain and could be related to undefined immunologic disturbance. Lesions can involve bone marrow, skin, oral mucosa, retro-orbital tissue, central nervous system, lymph nodes, spleen, liver, lung, and gastroenteric tract. Surgery, radiotherapy and chemotherapy can be employed as treatment. Prognosis is different in relation to the extension of the disease.

CASE REPORT: In our case (a 33 year old female) came to observation for swelling in temporal region. The patient underwent clinical and radiological examinations: the lesion involved the skull base in the right part of the sphenoid bone. CT and MRI showed a "clepsydra" lesion with wider extension to infratemporal fossa and to intracranial middle fossa and shrinking in the base of the skull; inside the lesion a lot of wider calcifications were present. A biopsy proved a diagnosis of Langerhans cell histiocytosis. No other localizations of disease were found. The patient was treated with chemotherapy followed by localized radiotherapy. Chemotherapy was performed with 3 cycles of etoposide 260 mg for 3 days every month. After this treatment a response of 25% was observed. Afterwards a radiotherapy with cobalt 60 was employed through two angled wedged fields for a total dose of 22 Gy and conventional fractionation. During the follow-up a slow, partial regression of the lesion with increase of the extension of the calcifications documented by CT and MRI was observed. After 5 years follow-up no progression of disease was observed.

DISCUSSION: The usual treatment of Langerhans cell histiocytosis is surgery and eventually radiotherapy for localized disease and chemotherapy for extended disease. The prognosis is related to the number of involved organs: usually favorable with only one site of disease and unfavorable when more organs are involved. Other unfavorable prognostic factors are the age < 2 years, the presence of anemia, liver and spleen involvement and respiratory failure. In our case only one site of disease was evident and the clinical behavior has been quite favorable. The main peculiarities are the radiologic aspect and the slow, partial regression after the treatment; this fact could be related to the presence of wide calcifications inside the lesion. After 5 years follow-up it is possible to consider the absence of progression as a response to the treatment.