Extragenital Bowen's disease (EBD) has rarely been studied for the presence of human papillomaviruses (HPVs). Twenty consecutive patients with EBD were investigated for the presence of HPVs using in situ hybridization with a generic probe that can detect HPV DNA types 6, 11, 16, 18, 30, 31, 33, 35, 45, 51, and 52 and specific probes for HPV DNA types 6/11, 16/18, and 31/33/35. All cases were tested with the polymerase chain reaction (PCR) technique employing the L1 consensus primer pair, MY11 (primer for the positive strand) and MY9 (primer for the negative strand) complementary to genital and dermal HPV types. Seven Caucasian patients, five males and two females, with an average age of 70.4 years, showed positive in situ hybridization (ISH) for HPV DNA. The positivity varied from 5 to 40% of neoplastic cells. Three of seven of the ISH DNA-positive cases showed a positive PCR for DNA HPVs. The role of HPVs in human tumors is not fully understood since oncogenic types of HPVs have been found in normal tissue and the actions of cofactors have been postulated. Bowen's disease usually occurs in elderly people in whom the efficiency of the immune systems may be compromised. The association between HPV infection and low efficiency of the immune response may be responsible for HPV-related Bowen's disease in elderly people.
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