Background:
Pituitary metastases occur in 1-4% of patients with metastatic disease, with breast and lung cancer accounting for over half of cases. 1,2 Carcinoma of unknown primary (CUP) is a carcinoma or undifferentiated neoplasm that through standard diagnostic investigations has not identified a primary tumour. 3 Survival rates in patients with CUP is historically poor. Incidence of CUP are declining as diagnostic methods become increasingly sophisticated, with recent analysis estimating CUP prevalence of <2% of all invasive cancers. 4
Clinical Case:
63-year-old female presented with worsening headache, nausea, and vomiting. Biochemistry revealed hyponatraemia (Na 122mmol/L), elevated serum prolactin (2163 mIU/L), central hypothyroidism (TSH 1.65 mIU/L, FT3 2.7 pmol/L, FT4 8.0pmol/L), and equivocal cortisol (247nmol/L). Physical examination was unremarkable with no visual field defects detected at the bedside, however, formal perimetry demonstrated bitemporal hemianopia. MRI pituitary confirmed a lobulated mass measuring 17x23x27mm with suprasellar extension causing compression of the optic chiasm, extension into sphenoid and cavernous sinuses and evidence of internal haemorrhage.
Patient underwent transsphenoidal resection of the pituitary lesion with no residual disease on post-operative imaging. Histological and immunohistochemical (IHC) findings were consistent with large cell carcinoma of unknown lineage though similar to that seen in renal cell carcinoma. Prolactin and other anterior pituitary hormone levels were normal post-operatively. Primary malignancy was not detected on investigations including CT CAP, FDG-PET, breast US, and endoscopies. Patient received adjuvant radiotherapy to the pituitary fossa with 50.4Gy in 28 fractions.
Discussion:
Despite IHC features similar to that of renal cell carcinoma no evidence to date has yielded evidence of a primary lesion. Favourable characteristics of CUP include single-site disease and renal-like CUP. 3
Conclusion:
We report a case of a sellar CUP that has to date achieved both local symptomatic control and disease free recurrence.