Functional cardiac paraganglioma associated with a rare SDHC mutation

Area of Science:

• Cardiology
• Oncology
• Genetics

Background:

• Paragangliomas are rare catecholamine-secreting tumors typically found outside the adrenal glands.
• Cardiac paragangliomas, particularly functional ones in the right atrium, are exceptionally uncommon, with limited literature available.
• This case involves a 41-year-old male presenting with a clinically functional cardiac paraganglioma.

Observation:

• A 9.5-cm cardiac mass and a 0.5-cm lung nodule were analyzed.
• Immunohistochemical profiling revealed positivity for chromogranin A and tyrosine hydroxylase, with a global loss of SDHB expression in both tumors.
• The MIB-1 labeling index was <5% in the smaller lesion and bulk of the larger lesion, with foci up to 10% in the larger lesion.

Findings:

• Genetic testing identified an intronic frameshift mutation in the SDHC gene (c.IVS 5+1, G>A).
• This represents the first reported case of a functional cardiac paraganglioma linked to an intronic SDHC gene mutation.
• Both the cardiac mass and lung nodule demonstrated shared immunohistochemical characteristics, suggesting a potential relationship.

Implications:

• This finding expands the known spectrum of genetic mutations associated with paragangliomas.
• Understanding the genetic basis of cardiac paragangliomas is crucial for diagnosis and potential targeted therapies.
• Further research into SDHC mutations and their role in cardiac paraganglioma development is warranted.