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Journal of Neuroradiology
Vol 26, N° 4  - décembre 1999
p. 277
Doi : JNR-03-2000-26-4-0150-9861-101019-ART6
Cas cliniques

Isolated histiocytosis x of the pituitary stalk

Cas clinique

Journal of Neuroradiology2000; 26: 277-280
© Masson, Paris, 1999

Tsutomu Asano (1), Yoshikazu Goto (1), Satoshi Kida (2), Kikuo Ohno (3), Kimiyoshi Hirakawa (3)

(1)Department of Neurosurgery, Saiyu Soka Hospital, Kitaya 1-22-13, Soka city, Saitama 340-0046, Japan.
(2)Department of Radiology, Dokkyo University School of Medicine, Minamikoshigaya 2-1-50, Koshigaya city, Saitama 343-8555, Japan.
(3)Department of Neurosurgery, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyou-ku, Tokyo 113-8510, Japan.


A case of histiocytosis X granuloma localized in the pituitary stalk is reported. Coronal and sagittal magnetic resonance imaging views were useful to determine the precise size and location of the mass lesion. The diagnosis was established immunohistochemically and the patient was treated with low-dose irradiation therapy.

After irradiation, the patient improved well without endocrine replacement treatment. The pituitary stalk recovered its normal size with no evidence of recurrence on MRI at 7-year follow-up.

We emphasize the importance of MRI before initiating therapy to evaluate the pituitary mass lesion and the effectiveness of low-dose irradiation for isolated histiocytosis X.

Key words : histiocytosis X. , pituitary stalk. , MRI. , low-dose irradiation.


Histiocytose X isolé de la tige hypophysaire

Nous présentons le cas d'un histiocytose X situé dans la tige hypophysaire. Les coupes coronales et sagittales de l'imagerie par résonance magnétique ont permis de préciser la taille et la topographie de la masse. L'immunohistochimie a confirmé le diagnostic et le patient a été traité par radiothérapie à faible dose.

L'évolution après la radiothérapie était favorable sans traitement de substitution et la taille de la tige hypophysaire est revenue à la normale. Aucune récidive est constatée à l'IRM de contrôle après un recul de 7 ans.

Nous soulignons l'importance de l'IRM préthérapeutique pour l'évaluation de la masse hypophysaire et pour contrôler l'efficacité de la radiothérapie à faible dose dans l'histiocytose X isolé.

Mots clés : histiocytose X. , tige hypophysaire. , IRM. , radiothérapie à faible dose.


Histiocytosis X is a non-neoplastic disorder of unknown etiology characterized by masses of proliferating histiocytes, plasma cells, and eosinophilic inflammatory cells forming granulomas within any organ system in the body [4]. Hypothalamic involvement as a complication of systemic histiocytosis X is not uncommon, but isolated form is rare and this entity is well known as the name of Gagel hypothalamic granuloma, Granuloma infiltrans of the hypothalamus, or Ayala's disease [3].

As the tumor of pituitary stalk, we must consider pituitary adenoma, Rathke's cleft cyst, craniopharyngioma, suprasellar germ cell tumor, hypothalamic glioma, and histiocytosis X.

In the present report, we will show a very rare case of histiocytosis X restricted to the pituitary stalk, and discuss the radiological imaging and refer to the treatment.

Case Report

This 24-year-old woman visited our department with a 2-month history of polydipsia, polyuria, and general fatigue. She was diagnosed diabetes insipidus (D.I.) of central origin by water deprivation test and vasopressin test, then treated with 20 microgram/day of 1-deamino-8-D-arginine vasopressin (DDAVP). She was a well-developed woman and had no other symptom of endocrine dysfunction except D.I. Neurological and neuroopthalmological examinations were normal. Her laboratory data including complete blood count, creatinine, and urinalysis were within normal limits. Endocrinological tests revealed no abnormality. Tumor markers (HCG, CEA and AFP) were not elevated.

Plain craniogram disclosed no abnormality (no calvarial lytic lesion, no sellar destruction). Enlarged pituitary stalk, which was about 5 mm in diameter, thicker than basilar artery, was present on axial view of enhanced computerized tomography (CT) image figure 1A . Coronal and sagittal views of magnetic resonance imaging (MRI) demonstrated round and thick pituitary stalk under the optic chiasma as iso-slightly high intense area on T1-weighted image, which was homogeneously enhanced with Gd-DTPA figure 1Bfigure 1C .

Generally it is difficult to differenciate parasellar tumors with MRI because of their variable signal intensity, but craniopharyngiomas & Rathke's cleft cysts are commonly high or low intense masses, whereas pituitary adenomas & gliomas are commonly iso-slightly low intense masses on T1-weighted image without Gd-DTPA. Germ cell tumors & granulomas have commonly iso-slightly high signal intensity on T1-weighted image.

Biopsy was performed through a right frontotemporal craniotomy, and the diagnosis of eosinophilic granuloma was obtained by histopathological examination. Microscopically, the tissue were composed of diffuse proliferation of histiocytes with pale cytoplasm, surrounded by many small lymphocytes, plasma cells, and occasional eosinophils figure 2 . These histiocytes were positively stained with an immunohistochemical stain for S-100 protein.

Then we treated her with a low dose irradiation therapy (total 20 Gy in 10 fractions over 2 weeks to the pituitary area). Six months after the irradiation, she became well without DDAVP, or other endocrine replacement. Further evaluations including bone scintigram and body CT scan showed no evidence of involvement elsewhere. The size of the pituitary stalk recovered normal (3 mm) soon after the irradiation, and no evidence of reccurence was shown on the MR imaging over a 7-year follow-up period figure 3Afigure 3B . Of course no radiation necrosis, nor radiation induced tumor has also been seen. She is now doing well with no endocrine dysfunction, no visual impairmet.


The classical triad of hypothalamic histiocytosis X were diabetes insipidus, endocrine deficiencies, and visual disturbance but they are not specific to the disease. And on the early stage initial manifestation is often diabetes insipidus only. Then isolated histiocytosis X of hypothalamus is difficult to diagnose, and this were mostly discovered by autopsy until about 1980 [7]. With the improvement of the neuroradiological examinations, we can now visualize a very small lesion with minimal clinical symptom as that in the present case.

In the CT study, it was reported that the size of the normal pituitary stalk is 2-3 mm, and the upper limit of this is 4 mm, which is smaller than basilar artery [9, 10]. In our case enlarged pituitary stalk, which was about 5 mm in diameter, thicker than basilar artery, appears as an iso density area on plain CT scan, and was homogeneously enhanced by contrast media.

T1-weighted MR images show iso-slightly high intensity mass lesion of the stalk, which was homogeneoulsy enhanced by Gd-DTPA, that is compatible to the demonstrated MR features of histiocytosis X [2, 11]. Sagittal and coronal MR images provided us the best anatomicotopographic evaluation of the lesion. The presence of mass is very clear and we can determine the precise size and location of the mass lesion, which was also available to the subsequent low dose irradiation therapy.

In our case, the extent of the tumor was determined by MR images & operative findings, but we can't deny the possible cell infiltration of hypothalamus and posterior hypophysis. Generally when the tumor invades the hypophysis, even a small invasion, some anterior endocrinological abnormality must be manifested as the report of Nishio et al. [6]. Similarly when the tumor extends upper side on the stalk, some visual disturbance must be confirmed by the trouble of chisma. In our case, these signs were not obserbed. But we can't discern microscopic infiltration. However irradiation is still effective even if the cells have infiltrated in hypothalamus and posterior hypophysis.

Treatments of histiocytosis X are controversial and are highly individualized . They included surgical removal, local irradiation, steroid administration, chemotherapy, and immune replacement therapy [1]. In case of single localized lesion, complete removal is the best choice [5]. But, when total removal is not possible because of the localization or the extent of the lesion, appropriate low dose irradiation (about 20 Gy) is recommended, which may bring good outcome. Histiocytosis X, in particular isolated form, is highly responsive to irradiation therapy, and there exists a strong expectation of complete regression after the irradiation [8]. In addition low dose irradiation therapy has low risk to damage the surrounding normal tissues. In our case, pituitary and visual functions were reserved, and no radiation necrosis, nor radiation induced tumor were obserbed during the follow-up period.

In conclusion, we emphasize the importance of MR imaging before surgical intervention, irradiation or chemotherapy to evaluate the small pituitary mass lesion, and the effectiveness of low dose irradiation therapy for isolated histiocytosis X.


Figure 1.
Contrast-enhanced axial computerized tomography scan of the patient.

(Les tableaux sont exclusivement disponibles en format PDF).

Figure 2.
Photomicrographs of the biopsy specimen showing diffuse proliferation of histiocytes with pale cytoplasm, surrounded by many small lymphocytes, plasma cells, and occasional eosinophils. (H & E, × 200).
Photomicrographes du prélèvement montrant la prolifération diffuse d'histiocytes avec un cytoplasme pâle au sein d'un amas de petits lymphocytes et de plasmocytes avec quelques eosiniphiles (H & E × 200).  

Figure 3.

(Les tableaux sont exclusivement disponibles en format PDF).


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