Autoimmune hypophysitis and viral infection in a pregnant woman: a challengeable case

The aim of this study is to report a challengeable and rare case of autoimmune hypophysitis possibly induced by viral infections. A young pregnant female developed optic neuropathy due to enlarged sellar mass responsible for hypopituitarism. Investigations exclude neoplasia and systemic diseases. High level of sedimentation rate and magnetic resonance imaging (MRI) findings supported the diagnosis of autoimmune hypophysitis. The patient reported a history of bronchitis treated with antibiotics and corticosteroids and positive serologies for hepatitis B antigen (Hbs antigen), herpes simplex 1 and rubella. Final examination showed complete recovery of visual function and sellar archnoidocele after antiviral treatment and mild dose of corticosteroids.


Introduction
Autoimmune hypophysitis (AH) is a rare autoimmune inflammatory disorder of the pituitary gland appeared as an enlarged mass resembling macroadenoma [1,2]. Treatment of this entity was corticosteroid [1,2]. Viral infections were widespread in all the world.
They may induce autoimmune diseases in such conditions [3]. Preview experimental studies and reviews reported factors inducing autoimmune hypophysitis including rubella and other viral infections [3][4][5]. We describe an unusual case of AH presumed to be induced by viral infections.

Discussion
In this report, clinical features, biological findings, and MRI supported the diagnosis of optic neuropathy due to an AH induced by viral infections. AH is a rare condition, usually seen in pregnancy or postpartum, characterized by sellar mass resembling adenoma and responsible for headache, visual impairment and variable degree of hypopituitarism [1,6]. Biologic features of AH included a high level of sedimentation rate [2,7]. In contrast to macroadenoma, sellar mass is symmetrical and homogeneous with thickened but undisplaced stalk [2,6]. Actually, studies strongly suggested a relationship Cochrane review concluded that adjunctive corticosteroid therapy in the treatment of influenza may be associated with increased mortality [8]. We give more attention to herpetic infection that was prevalent and may leading to severe cases of morbidity and neonatal mortality [9]. Authors reported that although there is no demonstrated benefit for prophylactic treatment in reducing the risk of neonatal herpes, anti-viral prophylaxis is recommended after 36 weeks of amenorrhea to limit the need for caesarean section [10]. The recommended antivirals are acyclovir at a dosage of 400mg until delivery. All data supported our use of acyclovir not only to improve the visual outcome but also to reduce neonatal complications [9,10].
Estimated incidence of AH is one in nine million per year. It occurs predominantly in young pregnant females, especially in the peripartum period [1,2]. It is classified as a primary hypophysitis that remained as a diagnosis of exclusion. Diagnosis of AH was considered when neoplasic pathology and secondary causes were ruled out [1,2].
Biopsy was made to distinguish between neoplastic and inflammatory causes. It requires surgery that is not always possible or necessary for an effective clinical management of the pathology [2,6].
Actually, hypophysitis can be differentiated from macroadenoma on MRI. Hypophysitis is a symmetrical, intensely and homogenously enhancing mass, with thickened but undisplaced stalk and intact sellar floor in contrast to typical findings with pituitary tumors [1,2,6].
Primary hypophysitis was classified into Lymphocytic Hypophysitis (AH) seen in the pregnant woman, granulomatous hypohysitsis due to granulomatous disease as sarcoidosis and tuberculosis, Xanthomatous Hypophysitis, IgG4-related disease and immune checkpoint therapy related hypophysitis induced by immunomodulatory therapy for cancer [2]. In this case, MRI findings in additions to clinical presentation of the disease, laboratory insipidus. Visual disorder was common (33%) but optic neuropathy was rarely seen [1,2,6]. Management of patients with AH consisted on replacement of hormonal deficiency and corticosteroids [2].
Authors reported the efficacy of pulses of corticosteroids (120 mg a day) in the management of AH. However, recurrence rate (38%) has been reported to be high and it highlights the limitations of this treatment [1]. Viral infection may explain the mechanism inducing this idiopathic disease. A previous experimental report concluded that pituitary gland may be susceptible to T cell mediated pathology after immunization of a virus expressing soluble pituitary gland antigen [4].
Besides, authors reported that rubella virus proteins extracted from vaccina virus recombinants induced AH [5]. In our case, at least three viral infections were encountered in the patient. Blurred vision seen after corticosteroids and rapid improvement with antivirals support this mechanism.

Conclusion
Autoimmune hypophysitis should be considered in any pregnant woman with sellar mass. Viral induction of this disease should be considered before starting corticosteroids.

Competing interests
The author declares no competing interests.

Authors' contributions
Kais Benabderrahim takes the responsibility of the manuscript and the management of patient.