Thyroid follicular renal cell carcinoma excluding thyroid metastases: A case report

Table 1 Comparison of the features of 41 cases with metastatic and non-metastatic thyroid-like follicular carcinoma of the kidney reported from 2006 to 2022

Features	Non-metastatic (n = 34)	Metastatic (n = 7)
Age (yr), mean ± SD (range)	41.7 ± 17 (10-83)	42.6 ± 14 (27-68)
Female sex	18/33 (55%; 1 unknown)	4/7 (57%)
Clinical presentation
Incidental	24 (71%)	4 (57%)
Flank pain/haematuria	10 (29%)	3 (43%)
History of malignancy (other sites)	8 (24%)	1 (14%)
Tumour characteristics
Size (cm), mean ± SD (range)	4.2 ± 2.3 (1.1-11.8)	5.3 ± 2.3 (3.5-10)
Right/left sided	17/16 (1 unknown)	5 2
Necrosis	9 (24%)	3 (43%)
Ki-67 proliferation index	1% to 30% (n = 6)	6% (n = 1)
pT stage
1a	20	3
1b	10	3
2a	1	0
2b	2	0
Immunohistochemical features
CK7	24/25 (96%)	5/6 (83%)
CK20	3/14 (21%)	2/4 (50%)
CD10	4/23 (17%)	1/5 (20%)
Vimentin	20/25 (80%)	3/4 (75%)
PAX8	10/11 (91%)	3/4 (75%)
Site of metastasis	-	Bone (2), lung (3), lymph node (2)
Follow-up period (mo)	22.1 ± 19.8	30.6 ± 28.8
Disease/death at follow-up	0	2 (28%)