Usefulness of Negative and Weak–Diffuse Pattern of SDHB Immunostaining in Assessment of SDH Mutations in Paragangliomas and Pheochromocytomas

Abstract

This is a confirmatory study about usefulness of SDHB and SDHA immunostaining in assessment of SDH mutations in paragangliomas and pheochromocytomas. Paraganglioma/pheochromocytoma syndrome (PGL/PCC syndrome) consists of different entities, associated with germline mutations in five different genes: SDHD, SDHAF2, SDHC, SDHA and SDHB. It has been suggested that negative immunostaining of SDHB can be taken as an indicator of the presence of a mutation in one of the five SDH genes. We have performed SDHB and SDHA immunohistochemical staining in a series of paragangliomas and pheochromocytomas from 64 patients. The patients had been previously checked for mutations in SDHD, SDHC and SDHB, but also for mutation in RET and VHL. All 14 patients with SDH mutations (9 with SDHB and 5 with SDHD mutations) exhibited negative or weak-diffuse SDHB staining pattern in tumour tissue, whereas cells of the 23 RET mutated and 8 VHL mutated tumours showed a positive SDHB immunostaining. Sixteen of the patients that did not exhibit a mutation in any gene showed positive SDHB immunostaining in tumour tissue, while only three of the patients without mutation exhibited negative staining. All patients exhibited positive pattern of SDHA immunostaining. The results confirm the value of SDHB immunohistochemical status in assessment of germline mutations in PGL/PCC syndrome.

SDHB/SDHA immunohistochemistry in pheochromocytomas and paragangliomas: a multicenter interobserver variation analysis using virtual microscopy: a Multinational Study of the European Network for the Study of Adrenal Tumors (ENS@T)

“…In parallel with recent advances in molecular genetics, immunohistochemistry has been shown to detect various types of molecular alterations, that is, BRAF V600E mutation in papillary thyroid carcinomas, 48 PTEN mutations in various neoplastic thyroid lesions, 49 CTNNB1 mutations in cribriform-morular variant of papillary thyroid carcinoma, undifferentiated carcinomas of the thyroid gland and adrenocortical carcinomas, 48,50,51 TP53 mutations as well as mutations in mismatch repair (MMR) genes such as MLH1, MSH2, MSH6, and PMS2 in adrenocortical carcinomas, [51][52][53] HRPT2 mutations in parathyroid carcinomas and hyperparathyroidism-jaw tumor syndrome-related adenomas, 48,54 PRKAR1A mutations in Carney complex-associated tumors, [55][56][57] and SDH-, FH-as well as MAX deleterious-mutations in pheochromocytomas/paragangliomas. 8,10,11,58,59 Loss of SDHB protein expression is seen in pheochromocytomas/paragangliomas either harboring a mutation in any of the SDH genes or with somatic hypermethylation of the SDHC promoter region, 42 whereas loss of both SDHB and SDHA immunoreactivity is demonstrated only in the context of an SDHA mutation. [8][9][10][11][12][13][14][15][16][17][18][19][20] In agreement with previous studies, 8,10,11,[17][18][19][20] SDHB-/C-/D-and SDHAmutated tumors displayed the aforementioned and NF1 mutations, 8,10 res...…”

“…8,10,11,58,59 Loss of SDHB protein expression is seen in pheochromocytomas/paragangliomas either harboring a mutation in any of the SDH genes or with somatic hypermethylation of the SDHC promoter region, 42 whereas loss of both SDHB and SDHA immunoreactivity is demonstrated only in the context of an SDHA mutation. [8][9][10][11][12][13][14][15][16][17][18][19][20] In agreement with previous studies, 8,10,11,[17][18][19][20] SDHB-/C-/D-and SDHAmutated tumors displayed the aforementioned and NF1 mutations, 8,10 respectively. By using a mouse monoclonal (21A11) SDHB antibody at a low concentration (1 in 1000), Gill et al 10 suggested that VHL-associated tumors could be classified as negative or weak diffuse rather than positive as demonstrated by a high concentration approach of two SDHB antibodies.…”

“…Van Nederveen et al 8 and Castelblanco et al 11 reported on 9 cases (6 out of 53; 11% and 3 out of 19; 15.7%) displaying loss of SDHB expression in the absence of SDHB, SDHC, SDHD, VHL, or RET mutation. Nevertheless, these studies lacked either SDHA/SDHAF2 genetic testing 8,11 or screening for large-scale SDH-x deletions 11 that may account for higher percentages. Intriguingly, in the present study, eight SDHB-immunonegative tumors were nonmetastatic in the absence of SDH-x mutations (Table 2), bearing a close resemblance to the Carney triad-associated counterparts in terms of SDHB immunohistochemistry and biologic behavior.…”

“…As loss of SDHB/ SDHA expression is predictive of an underlying SDH-x germline mutation, 8,10,11,17,[21][22][23][24]29,34,39 the role of SDHB/ SDHA immunohistochemistry has been underlined as a supplementary approach in molecular genetic testing especially for pheochromocytomas and paragangliomas. 8,10,11 As Sanger or targeted nextgeneration sequencing analysis of all pheochromocytoma/paraganglioma susceptibility genes is labor intensive and/or requires clinical molecular diagnostic laboratories, [43][44][45] it might be prudent to use immunohistochemistry to identify patients with succinate dehydrogenase-related pheochromocytoma/paraganglioma syndromes.…”

“…8,10,11 As Sanger or targeted nextgeneration sequencing analysis of all pheochromocytoma/paraganglioma susceptibility genes is labor intensive and/or requires clinical molecular diagnostic laboratories, [43][44][45] it might be prudent to use immunohistochemistry to identify patients with succinate dehydrogenase-related pheochromocytoma/paraganglioma syndromes. In addition, the presence of an SDHB mutation is one of the strongest predictors for both metastasis and subsequently poor outcome in pheochromocytomas/paragangliomas.…”