An acute adrenal insufficiency revealing pituitary metastases of lung cancer in an elderly patient

Metastases of solid tumors to the pituitary gland are often asymptomatic or appereas as with diabetes insipid us. Pituitary metastases more commonly affect the posterior lobe and the infundibulum than the anterior lobe. The presentation with an acute adrenal insufficiency is a rare event. A 69-year-old men presented with vomiting, low blood pressure and hypoglycemia. Hormonal exploration confirmed a hypopituitarism. Appropriate therapy was initiated urgently. The hypothalamic-pituitary MRI showed a pituitary hypertrophy, a nodular thickening of the pituitary stalk. The chest X Rays revealed pulmonary opacity. Computed tomography scan of the chest showed a multiples tumors with mediastinal lymphadenopathy. Bronchoscopy and biopsy demonstrated a pulmonary adenocarcinoma. Hence we concluded to a lung cancer with multiple pituitary and adrenal gland metastases. This case emphasizes the need for an etiological investigation of acute adrenal insufficiency after treatment of acute phase.


Introduction
Pituitary tumors are the most frequent intracranial neoplasm, affecting 11000 of the worldwide population [1]. However metastases in this location are rare and uncommon presentation of systemic malignancy. The clinical and radiologic features of most pituitary metastases can be characteristic and evocative but in no case pathognomic. The diabetes insipidus is the most common clinical manifestation of the disease [2,3]. We report herein a case of an acute adrenal insufficiency revealing pituitary metastases of lung cancer.

Patient and observation
A 69-year-old patient active smoker with history of type 2 diabetes mellitus presented with signs of acute adrenal insufficiency; vomiting, low blood pressure and hypoglycemia, associated to a polyuro polydipsic syndrom. Assessment of pituitary function revealed hypopituitarism and an insipidus diabetes; serum cortisol level of 12.6 ng/mL (normal range 100-250 ng/mL), Free T4 level of 6.8 pg/mL (normal range 8-18 pg/mL), thyroid stimulating hormone level of 0.005mUI/mL (normal range 0.5-4 IU/mL), total testosterone level of 0.025 ng/mL (normal range 2.5-10 ng/mL), follicle stimulating hormone level of 0.5 IU/mL (normal range 1-8.

Primary tumors
Breast and lung carcinomas represent the most frequent tumors that metastasis on a normal pituitary or on a pituitary adenoma.

Clinical findings
The majority of pituitary metastases are clinically silent. Only 7% of pituitary metastases were symptomatic. Among symptomatic patients, diabetes insipidus is the most frequently reported finding, with a variable incidence ranging from 29% to 81%. Other symptoms are essentially represented by ophthalmoplegia, headache/pain, vomiting, visual field defects, decreased Page number not for citation purposes 3 consciousness, and anterior pituitary dysfunction [7]. These symptoms can be the manifestation of a pituitary apoplexy.
Although pituitary apoplexy usually occurs in patients with preexisting pituitary macroadenoma, it has also been described in those with a normal pituitary gland, craniopharyngioma, lymphocytic hypophysitis and, in rare instances (<5%), pituitary metastasis [8].
The diagnosis is made in front of clinical signs and confirmed by with possible histopathological examination.

Physiopathology
The explanation for metastatic tumor localization to pituitary is not where the first symptoms reveal an acute adrenal insufficiency whose treatment has uncovered a diabetes insipidus.

Radiologic findings
MRI is the preferred technique to demonstrate pituitary metastases [8]. However, the question is how to differentiate pituitary metastasis from pituitary adenoma in patients with a history of malignant disease, but also in those in which pituitary metastasis is the initial symptom of a malignant disease. Some radiological characteristics have been reported to be helpful in differentiating pituitary metastases from pituitary adenomas; these include the following: 1) thickening of the pituitary stalk; 2) loss of a high-intensity signal from the posterior pituitary; 3) isointensity on both T1-and T2-weighted magnetic resonance images; 4) invasion of the cavernous sinus; and 5) sclerotic changes around the sella turcica.
Clinically, the presence of diabetes insipidus is very suggestive of pituitary metastasis and can be the first manifestation of a malignant neoplasm. Although history or coexistence of malignancy usually leads to the diagnosis, it is of limited diagnostic value because 1.8 to 16 percent of patients with known malignancy and a sellar tumor turn out to harbor a pituitary adenoma [9].

Treatment
Treatment, mostly palliative, depends on symptoms. It is usually limited and includes palliative radiotherapy, hormone replacement therapy when indicated and/or chemotherapy for the primary cancer. Surgical exploration and decompression, alone or combined with radiation, is often necessary when suprasellar extension causes progressive deterioration in vision and/ or pain [9].

Prognosis
The prognosis of metastatic cancer to pituitary adenoma is grim, as most patients already have widespread metastases at the time of diagnosis. The mean survival after the development of pituitary metastasis is only six months, with an overall 1-year mortality rate of more than 90% [2]. Our patient received adjuvant chemotherapy and if possible radiotherapy on the pituitary gland.

Conclusion
Despite the fact that pituitary metastasis are rare, they must be evoked on the presence of pituitary involvement, sudden onset of adrenal insufficiency, even in the absence of a neoplastic history.
Pituitary tumor and / or metastasis should be taken in account in differential diagnosis.

Competing interests
The authors declare no competing interests.

Authors' contributions
Dr Hela Marmouch is responsible for writing this paper and Dr Sondes Arfa contributed to the drafting of the paper. All authors contributed to the patient's care and approved the final paper.