Multiple endocrine neoplasia type 2B

Multiple endocrine neoplasia type 2B

Epidemiology and genetics - This has a prevalence of 0.2 in 100 /uni00A0 000. MEN /uni00A0 2B is also caused by RET mutations, half of which are de novo . Clinical presentation A variant of MEN /uni00A0 2 characterised by an aggressive and early-onset form of MTC (100%), PPGL (59%), marfanoid - habitus and ganglioneuromatosis of the oral mucosa and gut ( Figure 57.19 ). MTC is associated with rapid growth and a poor prognosis. Surgery for MEN types 2A and 2B Kindred of known MEN /uni00A0 2 patients are tested for the presence of a mutation. MEN /uni00A0 2B infants should undergo a thyroid ectomy in the first year of life. Children who carry mutations are screened for calcitonin, which can detect the presence of the precursor to MTC – C-cell hyperplasia. This allows a thyroidectomy to be undertaken before invasive MTC has developed (so-called prophylactic thyroidectomy) (see also Chapter 55 ). Owing to the strong genotype–phenotype relationship, the specific mutations guide clinicians with regard to the timing of prophylactic surgery ( Table 57.9 ).

Figure 57.19 Ganglioneuromatosis of the oral mucosa in multiple endocrine neoplasia type 2B. TABLE 57.9 Risk of medullary thyroid carcinoma and genetic mutations in multiple endocrine neoplasia syndromes. Age of Risk level, Age of RET Age of prophylactic codon testing required /f_i rst surgery calcitonin As soon as 6 months if D, 918; 804 As soon as possible, not already possible, within /f_i rst done within /f_i rst year of life year of life C, 634 <3–5years

3–5years Before 5 years B, 609, 611, <3–5years 3–5years Consider 618, 620 before 5 years, may delay A, 833, 819, <3–5years 3–5years Between 10 891, 912 and 15 years