Allah Rakha Adil, Jawad Gilani, Aakif U Khan.
Pituitary Metastases from differentiated thyroid carcinoma.
J Coll Physicians Surg Pak Jan ;12(1):60-1.

A middle aged woman with known metastatic papillary thyroid carcinoma presented with right sided squint and generalized headache. History and physical examination revealed no neurological deficit other than right medial squint and slow progression of headache. She had no visual impairment on ophthalmological consultation. X-ray skull showed an undefined area of focal haziness in the pituitary region. An irregularly outlined radio-opaque lesion involving almost whole of the pituitary area was clearly visible on CT scan of skull. Scintigraphic studies with I-131 and Tc-99m MIBI showed an area of increased tracer uptake at sella turcica although bone scan with Tc-99m MDP was normal. Her serum thyroglobulin (s-Tg) level was >300 ng/mL. Histopathological examination of the biopsied specimen proved its origin from thyroid tissue. This report demonstrates that papillary thyroid carcinoma can metastasize to the pituitary region even without concurrent involvement of bone. Despite extensive metastatic involvement, overall neurological deficit may not keep pace with the extent of tumor spread.

Case Report: A 40 years old female with biopsy proven differentiated thyroid carcinoma thyroid for the last 3 years came to us with history of right sided squint of recent origin with generalized headache. On clinical inquiry, headache was slow in progression, dull in character and more after waking in the morning. There was past history of sub-total thyroidectomy followed by ablation by I-131 three years ago. Her previous follow-up of whole body scans with I-131 were normal with no evidence of any residual or metastatic thyroid tissue. Physical examination revealed no neurological deficit other than right medial squint. She had no visual impairment on ophthalmologic consultation. X-ray skull showed an undefined area of focal haziness in the pituitary region. An irregularly outlined radio-opaque lesion involving almost whole of the pituitary area and extending laterally towards cavernous sinuses was clearly visible on CT scan of skull. Most probably this squint was due to involvement of cranial nerves lying in the lateral wall of one of the cavernous sinus. She was sent to the department of nuclear medicine of IRNUM where Tc-99m MIBI WBS (whole body scan) was performed. The scan revealed an area of increased tracer uptake in the pituitary area of skull, chest and one cervical lymph node. As she was already a diagnosed case of DTC (differentiated thyroid carcinoma), these foci of abnormal tracer uptake were suspected of metastases from thyroid. So she was performed I-131 WBS. Its findings were consistent with that of Tc-99m MIBI scan. Pituitary region uptake was further confirmed by placing two hot sources of radiotracer to augment the localization of lesion. Her blood sample collected before I-131 WBS (whole body scan) showed serum thyroglobulin >300 ng/ml (normal is 55 ng/ml). Histopathological outcome of biopsied tissue from this pituitary lesion proved its origin from thyroid. As mentioned earlier that whenever there is big remnant or recurrent thyroid tissue, it rather masks the localization of other small metastatic foci. So it was possible that due to these recurrent and metastatic lesions in the pituitary region, lungs, thyroid bed and lymph node , small metastases in bone (more common site of metastases from differentiated thyroid carcinoma) might have been missed on the first scan. Scan Repiat with 1-131 was done after surgery and removal of recurrent tissue in thyroid bed, which did not show any other focus of increased tracer uptake anywhere else in the body. Her bone scan also came out to be normal.

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