Other types of HPV (18, 31, 32, 33, 34, 35, 39, 42, 48, 51, 52, 53, and 54) have also been implicated
Clinical Issues
• Often multifocal
• Benign-looking papules and macules with flat surface
Often slightly pigmented
May show verruciform surface
Rare linear presentation has been described
• Affect labia majora in females
• Usually affect skin of shaft in males
• Extragenital lesions are exceptional
• Lesions affecting young healthy patients usually regress spontaneously
• Risk of progression to invasive disease is related to
Older age
Immunosuppression
Perianal location
Microscopic
• Proliferation of atypical basaloid and koilocytic cells arranged as
Scattered single units or patches
Involving full thickness of epithelium
• Granular layer may be preserved
• Ortho- or parakeratosis
• Most cases are indistinguishable from SCCis
Top Differential Diagnoses
• Vulvar and penile intraepithelial neoplasia (VIN and PeIN)
Despite benign appearance, BP may be identical to VIN and PeIN histologically
Clinical correlation is crucial to make distinction
• Treated condyloma
Pallor of epithelium, nuclear enlargement, necrotic keratinocytes
Increase number of mitotic figures (metaphase arrest)
No atypical mitosis
Early Lesion of Bowenoid Papulosis At low-power examination of an early lesion, the changes may be subtle, and the condition may be difficult to distinguish from a flat condyloma.
Bowenoid Papulosis With Basilar Hyperpigmentation Patchy foci of full-thickness keratinocytic atypia are usually seen in bowenoid papulosis. Atypical cells vary from small basaloid to larger and more pleomorphic with koilocytic-like changes . Note the hyperpigmentation of the basal layer .
Bowenoid Papulosis at Higher Magnification Bowenoid papulosis shows atypical keratinocytes throughout the full thickness of the epithelium. There are several mitoses and koilocytic change.
Bowenoid Papulosis at High Magnification Higher power view shows atypical basaloid and koilocytic cells replacing the epidermis. Despite the atypical features, the granular layer is preserved , and there is overlying orthokeratosis .
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to larger and more pleomorphic with koilocytic-like changes 
. Note the hyperpigmentation of the basal layer 
.
and koilocytic change.
, and there is overlying orthokeratosis 
.
