Panpituitary lymphocytic hypophysitis
Past history of chronic lymphocytic leukaemia (CLL) in remission. Now unwell and visual changes.
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The pituitary gland and stalk are replaced by vividly homogeneous enhancing tissue, with absent normal posterior pituitary bright spot. The stalk is moderately thickened and lobulated, and there is superior extension to the hypothalamus. The chiasm is superiorly displaced, and the adjacent optic nerves are slightly splayed.
No evidence of cavernous sinus involvement.
Five small enhancing lesions are noted: left cerebellum, left pons, left temporal and frontal lobes, and right lentiform nucleus.
Findings are of infundibular and pituitary infiltration with multifocal parenchymal and/or subarachnoid involvement. Differentials include malignancy (lymphoma/haemoproliferative spectrum including CLL, metastasis less likely if no known primary), low grade/indolent atypical infection (in the setting of immunosuppression) or inflammatory (including granulomatous: sarcoid, Erdheim Chester/histiocytosis, IgG4 disease.
Although lymphocytic hypophysitis can have this appearance, including extra-pituitary involvement, the demographics of this patient are less typical.
The patient went on to have a transsphenoidal biopsy.
The sections include anterior pituitary gland tissue and stroma. There is prominent lymphoid infiltrate with intermixed markedly atrophic anterior pituitary gland tissue. The stroma shows fibrosis. The inflammation comprises mainly lymphocytes. Plasma cells are inconspicuous. There are no granulomas or giant cells. The lymphoid cells appear small and mature with no nuclear atypia. There is no evidence of pituitary adenoma. No evidence of malignancy is seen. No organisms are noted.
The lymphocytes are mainly CD3+ T-cells. CD4 to CD8 ratio is 1 to 1, which is normal. There are no abnormal CD20/CD5/CD23 positive cells to indicate small lymphocytic lymphoma/chronic lymphocytic leukemia. PAX-5, BOB-1 and OCT-2 are negative (all B-cell markers). IgG4 is also negative.
The Grocott stain shows no fungi. The Ziehl-Neelsen stain shows no acid fast bacilli. No viral inclusions are seen.
- Calcofluor white stain: no fungal elements detected
- Gram stain: Leukocytes +; no organisms seen
- Auramine-Rhodamine Stain: no acid-fast bacilli detected
- bacterial: no growth
- nocardia: no growth
- fungal: no growth
- mycobacterial: no growth
- Toxoplasma: not detected
- 16S rRNA bacterial identification: not detected
- panfungal PCR: not detected
- mycobacterial: not detected
Reactive chronic T-lymphocytic infiltrate and fibrosis.
Although the morphology cannot distinguish between primary or secondary hypophysitis, the absence of systemic disease, infection and malignancy would make the diagnosis of primary hypophysitis almost certain. The presence of extra-pituitary lesions, however, does raise some questions about the final diagnosis.
Nonetheless, this case demonstrates important features of panpituitary infiltration.