Key-words:
Anti-tubercular therapy - hormone replacement - pituitary tuberculoma - sellar adenoma
Introduction
Tuberculosis is an important cause of mortality and morbidity across the world. The
involvement of hypothalamo–pituitary axis by tuberculosis is rare.[[1]] It presents with features of pituitary insufficiency and signs of pressure effects
due to compression of optic chiasma or cavernous sinus. Tuberculous sellar mass can
eventually result in permanent endocrine dysfunction, if diagnosis is delayed. The
need to investigate early is crucial since endocrine dysfunction is reversible with
anti-tubercular therapy.[[2]] Clinicians need to be aware of tuberculosis as a possibility in any nonsecreting
pituitary lesion. Histopathological examination of the lesion always gives us the
final diagnosis.
Case Report
A 31-year-old female presented with complaints of secondary amenorrhea, loss of appetite,
and weight loss in the past 1 year associated with multiple episodes of vomiting of
3 days duration. She had two episodes of severe vomiting requiring hospitalization
in a span of 7 months. There were no complaints of any visual symptoms. On examination,
higher mental functions, cranial nerves, motor and sensory systems were normal. There
were no signs of meningitis. Ophthalmology opinion was sought and it revealed normal
visual acuity and visual fields. Laboratory investigations revealed secondary hypocortisolism,
hypothyroidism, and hyponatremia with normal prolactin level. Subsequently, endocrinology
opinion was sought and she was started on corticosteroids and L-thyroxine. Magnetic
resonance imaging (MRI) brain showed features of enlarged pituitary fossa, T1/T2-weighted
hyperintense solid enhancing mass lesion approximately 10.5 mm × 16 mm × 14.6 mm with
superior extension into suprasellar cistern with enhancement of pituitary stalk [[Figure 1]]. The lesion was causing mild compression and superior displacement of optic chiasma
by 3 mm. The lesion was seen bulging into cavernous sinuses bilaterally just abutting
internal carotid arteries with no invasion. There was uniform enhancement of the lesion
contrary to ring enhancement seen in tubercular lesions [[Figure 2]].
Figure 1: Magnetic resonance imaging of brain showing isointense sellar lesion with enhancement
of pituitary stalk
Figure 2: Magnetic resonance imaging of brain showing uniform enhancement of sellar lesion
in contrary to ring enhancement seen in tuberculoma
She underwent endoscopic transnasal transsphenoidal pituitary tumor excision under
general anaesthesia. Intraoperatively, the sella was abnormally low lying and thickened,
tumor was avascular and fibrous in consistency and was excised preserving the normal
arachnoid membrane with no cerebrospinal fluid (CSF) leak. Histopathological examination
revealed tissue fragments composed of numerous epithelioid granulomas, some with central
caseous necrosis and occasional Langhans' giant cells [[Figure 3]] and [[Figure 4]]. Periphery showed dense lymphocytic infiltrate mixed with plasma cells and fibrosis.
Stroma showed few glands lined by cuboidal cells. Acid-fast bacilli stain was found
to be negative. The features were consistent with granulomatous inflammation suggestive
of tubercular etiology. Perioperative period was uneventful except for transient diabetes
insipidus. Postsurgery, the patient was started on anti-tubercular and hormonal replacement
therapy. She is on regular follow-up since the past 3 months and is recovering without
any sequelae.
Figure 3: Diffuse granulomas composed of epithelioid cells, lymphocytes, and plasma cells replacing
the pituitary gland ͯ100 (H and E)
Figure 4: Epithelioid granulomas with central caseous necrosis ͯ400 (H and E)
Discussion
Central nervous system tuberculosis contributes to 1% of tuberculosis cases worldwide.[[3]] The first report of intrasellar tuberculoma was published by Coleman et al.[[4]] Intracranial tuberculomas contribute to 0.15%–4% of intracranial space-occupying
lesions. Kim et al.[[5]] stated that pituitary tuberculous infection disseminates by hematogenous route,
direct extension from paranasal sinus, or secondary to tuberculous meningitis. The
past history or active tuberculous infection elsewhere in the body was seen in 30%
of patients.
Srisukh et al.[[3]] have published a series of 81 case reports of pituitary tuberculoma, of which mean
age of presentation was 34.1 ± 13.6 years (range 8–68 years) with more incidence in
females (72.8%). The most common presenting symptom was headache (85.2%) followed
by visual disturbances (48.1%). Endocrine disturbances were the initial presenting
symptoms and included galactorrhea (23.7% of female), amenorrhea (37.3% of female),
and polyuria from central diabetes insipidus (8.6%). Central diabetes insipidus was
an important factor in differentiating pituitary tuberculoma from pituitary adenoma.
Rajasekaran et al.[[6]] have reported the incidence of pituitary apoplexy being around 2%–7% in cases of
pituitary adenoma characterized by acute infarction and/or hemorrhage of the pituitary
gland. Deogaonkar et al.[[7]] have reported that pituitary tuberculoma presenting as apoplexy is extremely rare.
Mascarenhas et al.[[2]] have stated that on MRI, tuberculous pituitary lesions appear isointense to hypointense
on T1-weighted images, hyperintense on T2-weighted images with occasional hyperintensity
seen on T1-weighted images due to their high protein content. These are nonspecific
and can overlap with pituitary adenomas and other granulomatous lesions. Tuberculous
abscess can have peripheral contrast enhancement and adjacent meningeal enhancement
on contrast-enhanced MRI. Contrast MRI showing typical changes of thickening and enhancement
of pituitary stalk could be an important pointer in diagnosis.[[3]],[[8]] Pituitary tuberculoma can be managed conservatively, if confirmed by CSF polymerase
chain reaction for tuberculosis if coexistent with an active tuberculous meningitis.[[3]]
The main intention of surgery is to have tissue diagnosis and for surgical decompression
to relieve pressure symptoms. The transsphenoidal approach is routinely followed as
it permits both tissue diagnosis and tumor decompression without CSF contamination.
Intraoperative findings of a thickened hypophyseal stalk, grayish firm nonsuckable
mass with caseation and a thickened dura, are significant signs of a tuberculous lesion.[[2]] Histopathological features are confirmatory and are characterized by a central
area of caseation necrosis surrounded by epithelioid cells, lymphocytes, plasma cells,
and Langhans' giant cells. Acid-fast bacilli are usually not seen.[[2]]
In all sellar region masses, differential diagnosis such as adenoma, cyst of Rathke's
pouch, craniopharyngioma, glioma of the optic chiasma or hypothalamus, meningioma,
germ cell tumor, hamartoma, lipoma, dermoid or epidermoid cyst, metastasis and granulomatous
conditions such as lymphocytic hypophysitis, sarcoidosis, tuberculoma, and Langerhans
cell histiocytosis should be borne in mind. Nevertheless, distinctive MRI features,
including contrast MRI showing typical changes of thickening and nodularity of the
pituitary stalk and ring enhancing lesion can guide diagnosis.[[1]],[[9]],[[10]]
A high index of preoperative suspicion with history and radiological features, avoidance
of transcranial approach, minimally invasive surgical techniques and prevention of
CSF contamination with mycobacterial organisms are important pearls in management.
Anti-tubercular therapy is mandatory and the need for hormone replacement therapy
is decided based on patient's pre- and post-operative pituitary hormonal status. Anticipated
symptoms of pituitary insufficiency following surgery can be avoided by limiting the
extent of surgery.[[2]]
Despite being a rare entity, it is important to consider pituitary tuberculoma as
a differential diagnosis in patients with sellar lesions with distinctive radiological
features. Prompt recognition, early diagnosis and commencement of the anti-tuberculosis
regimen, postoperative hormone replacement therapy can have good results with significant
improvement of symptoms.
