An immunohistochemical procedure to detect patients with paraganglioma and phaeochromocytoma with germline SDHB, SDHC, or SDHD gene mutations: a retrospective and prospective analysis

Abstract

Background: Phaeochromocytomas and paragangliomas are neuro-endocrine tumours that occur sporadically and in several hereditary tumour syndromes, including the phaeochromocytoma-paraganglioma syndrome. This syndrome is caused by germline mutations in succinate dehydrogenase B (SDHB), C (SDHC), or D (SDHD) genes. Clinically, the phaeochromocytoma-paraganglioma syndrome is often unrecognised, although 10-30% of apparently sporadic phaeochromocytomas and paragangliomas harbour germline SDH-gene mutations. Despite these figures, the screening of phaeochromocytomas and paragangliomas for mutations in the SDH genes to detect phaeochromocytoma-paraganglioma syndrome is rarely done because of time and financial constraints. We investigated whether SDHB immunohistochemistry could effectively discriminate between SDH-related and non-SDH-related phaeochromocytomas and paragangliomas in large retrospective and prospective tumour series.

Methods: Immunohistochemistry for SDHB was done on 220 tumours. Two retrospective series of 175 phaeochromocytomas and paragangliomas with known germline mutation status for phaeochromocytoma-susceptibility or paraganglioma-susceptibility genes were investigated. Additionally, a prospective series of 45 phaeochromocytomas and paragangliomas was investigated for SDHB immunostaining followed by SDHB, SDHC, and SDHD mutation testing.

Findings: SDHB protein expression was absent in all 102 phaeochromocytomas and paragangliomas with an SDHB, SDHC, or SDHD mutation, but was present in all 65 paraganglionic tumours related to multiple endocrine neoplasia type 2, von Hippel-Lindau disease, and neurofibromatosis type 1. 47 (89%) of the 53 phaeochromocytomas and paragangliomas with no syndromic germline mutation showed SDHB expression. The sensitivity and specificity of the SDHB immunohistochemistry to detect the presence of an SDH mutation in the prospective series were 100% (95% CI 87-100) and 84% (60-97), respectively.

Interpretation: Phaeochromocytoma-paraganglioma syndrome can be diagnosed reliably by an immunohistochemical procedure. SDHB, SDHC, and SDHD germline mutation testing is indicated only in patients with SDHB-negative tumours. SDHB immunohistochemistry on phaeochromocytomas and paragangliomas could improve the diagnosis of phaeochromocytoma-paraganglioma syndrome.

Funding: The Netherlands Organisation for Scientific Research, Dutch Cancer Society, Vanderes Foundation, Association pour la Recherche contre le Cancer, Institut National de la Santé et de la Recherche Médicale, and a PHRC grant COMETE 3 for the COMETE network.

Figure 1. SDHB immunohistochemistry

Phaeochromocytoma and paraganglioma SDHB immunohistochemistry. (A) Phaeochromocytoma with SDHB mutation. (B) Paraganglioma with SDHC mutation. (C) Paraganglioma with SDHD mutation. (D) Phaeochromocytoma with VHL mutation. (E) Phaeochromocytoma with RET mutation. (F) Phaeochromocytoma from a patients with NF1 (clinical diagnosis). Note: Strong speckled SDHB immunostaining in non-SDH mutated tumours (D, E, and F). Absence of SDHB immunostaining in the tumour cells of SDHB, SDHC, and SDHD-mutated tumours, with positive staining in the normal cells of the intratumoral fibrovascular network (A, B, and C). In the SDHD-mutated tumour (C) diffuse cytoplasmic background staining is seen, clearly distinct from the staining of the intratumoral fibrovascular network.

Figure 2. Western blotting and enzyme histochemical results

(A) Western blot result with SDHB antibodies from Novus Biologicals NB600-1366 (SDHB I) and Sigma HPA002868 (SDHB II) and β-actin of phaeochromocytoma with different mutations. SDHB case: SDHB exon 3 deletion; SDHD case: SDHD p.Asp92Tyr missense mutation; RET case: RET p.Cys634Arg missense mutation; VHL case: VHL p.Arg64Pro missense mutation; NF1 case: clinically defined NF1. *Normal is a lysate from a lymph node from the patient with the SDHB mutation. ^†Normal is a lysate from a healthy adrenal gland. SDH-enzyme histochemistry results: (B) loss of SDH activity in tumour cells of a phaeochromocytoma with a SDHD p.Asp92Tyr mutation, but retained activity in the normal cells of the intratumoral fibrovascular network (arrow); (C) strong SDH activity in tumour and normal cells of a phaeochromocytoma with a RET p.Cys634Arg mutation.

Figure 3. Suggested algorithm for molecular genetic testing for phaeochromocytoma and paraganglioma

The presence of familial or clinical criteria for a phaeochromocytoma-associated or paraganglioma-associated inherited disease should lead to targeted genetic testing. In the absence of criteria, SDHB immunohistochemistry is indicated. A positive SDHB immunohistochemistry result should lead to VHL and RET genetic testing, a negative SDHB immunohistochemistry should lead to SDH (SDHD, SDHB, and SDHC) genetic testing, starting with SDHD in cases of head and neck paraganglioma or starting with SDHB in cases of thoracic–abdominal or pelvic paraganglioma.