April 13, 2023
A 14-year-old adolescent girl presents with headache, weight loss, polyuria, and polydipsia. On admission, laboratory workup demonstrates panhypopituitarism.
IgG4-Related Hypophysitis
Background:
- IgG4-related hypophysitis is a pituitary manifestation of IgG4-related disease, a disease characterized by tumor-like involvement of multiple organs with IgG4-positive plasma cells.
Clinical Presentation:
- The patient typically presents with hypopituitarism (diabetes insipidus and/or anterior pituitary hormone deficiencies).
- The other main presenting symptoms are due to local mass effect, including vision changes and headaches.
Key Diagnostic Features:
- MRI demonstrates loss of the normal posterior pituitary T1 bright spot, a sellar mass, and thickening and enhancement of the infundibulum.
- Imaging is required to assess for systemic manifestations of IgG4-related disease outside the brain; this includes the orbits, paranasal sinuses, salivary glands, thyroid, lungs, pancreas, and kidneys.
- Although serum IgG4 levels are often elevated, more definitive diagnosis requires histopathologic analysis of the pituitary or other affected organ, which demonstrates lymphoplasmacytic infiltration of predominantly IgG4-positive plasma cells (proposed cutoffs include IgG4+/IgG+ plasma ratio of >40%, however, this varies by organ).
Differential Diagnoses:
- Lymphocytic hypophysitis: Seen in the pregnancy/early postpartum period
- Infectious granulomatous hypophysitis, such as tuberculosis: Presence of systemic illness
- Granulomatosis with polyangiitis: Associated findings in the sinuses (erosion of the nasal septum/turbinates) and lungs (nodules or consolidation with or without cavitation).
- Neurosarcoidosis: Seen in the presence of other typical CNS findings (pachymeningeal or leptomeningeal involvement) and chest findings (hilar adenopathy)
- Langerhans cell histiocytosis: Classically associated lytic calvarial lesions with beveled edges
- Germinoma: May be multifocal and involve the pineal region
- Lymphoma: Can be primary or secondary; when the pituitary is involved, there is typically an aggressive appearance with potential involvement of the skull base, cavernous sinus, and cranial nerves
- Metastasis: Typically seen in adults with known primary tumor
Treatment:
- IgG4-related hypophysitis typically demonstrates rapid response to corticosteroid therapy.
- Treatment also entails managing pituitary dysfunction with hormone replacement.
