A review of the records of the outpatient department of the Boston City Hospital for the years 1908 to 1930,1 inclusive, showed 691 cases in which a diagnosis of primary syphilis was made; extragenital chancre was observed in 38 cases, approximately 6 per cent.
The location of these chancres is shown in the following tabulation:
Downing JG. INCIDENCE OF EXTRAGENITAL CHANCRES. Arch Derm Syphilol. 1939;39(1):150. doi:10.1001/archderm.1939.01480190153014