How can I differentiate a hyperkeratotic papule from a wart?

Differentiating Hyperkeratotic Papules from Warts

The key diagnostic maneuver is paring down the lesion: warts will demonstrate pinpoint bleeding from exposed capillary loops, while hyperkeratotic papules (corns, calluses) will not bleed and reveal a smooth, translucent core or diffuse thickening. 1

Primary Diagnostic Features

Warts (Verruca Vulgaris)

• Pinpoint bleeding upon paring is pathognomonic for warts, occurring as thrombosed capillaries in elongated dermal papillae are exposed 1, 2
• Appear as well-circumscribed, flesh-colored growths with a white pebbly or papillary surface 1, 3
• Disruption of normal skin lines (dermatoglyphics are interrupted) 4
• May show black dots (thrombosed capillaries) on the surface, which strongly predict HPV presence 5
• Can persist for 5-10 years in adults with minimal inflammation, developing thick hyperkeratotic overlying changes 2, 3

Hyperkeratotic Papules (Corns/Calluses)

• No bleeding upon paring; instead reveal a central translucent core (corns) or smooth surface (calluses) 1, 2
• Corns present as hard, yellow lesions with a central nucleus or plug of keratin extending downward in a cone shape 2
• Located specifically on pressure points: tips of toes, underneath metatarsal heads, or weight-bearing surfaces 2
• Calluses appear as diffuse thickened areas without a central core, generally less painful than corns 2
• Preservation of skin lines through the lesion 2

Dermoscopic Examination

When clinical examination is equivocal, dermoscopy provides additional diagnostic clarity:

Wart Features on Dermoscopy

• Papillomatous growth pattern (seen in 42% of clinically nonclassical common warts) 4
• Dotted or linear vessels in a regular pattern 4
• Hairpin-like vessels 4
• Bleeding spots (thrombosed capillaries) 4

Hyperkeratotic Papule Features

• Structureless yellowish appearance without vascular patterns 4
• Homogeneous translucent core in corns 2

Location-Based Considerations

On the feet: Plantar warts must be distinguished from corns and calluses through paring and close inspection 1. The pain quality differs—corns cause pain described as "walking on a small stone or pebble" due to the central core pressing into dermis 2, while warts cause more diffuse discomfort.

On hands/limbs: Warts show characteristic hyperkeratosis with a heavy granular layer and koilocytes histologically 1, while other hyperkeratotic lesions like lichen planus or knuckle pads lack these features 1.

Critical Diagnostic Algorithm

1. Pare down the lesion with a scalpel blade after cleaning 1

   • If pinpoint bleeding occurs → Wart 1, 2
   • If smooth translucent core or no bleeding → Corn/callus 2

2. Assess skin line disruption 4

   • Lines interrupted → Favors wart
   • Lines preserved → Favors hyperkeratotic papule

3. Evaluate location and pain pattern 2

   • Pressure point with "pebble" sensation → Corn
   • Non-pressure point or diffuse discomfort → Consider wart

4. If diagnosis remains uncertain after paring, perform dermoscopy looking for vascular patterns (wart) vs. structureless appearance (hyperkeratotic papule) 4

Important Caveats

• Long-standing warts (>2 years) may lose characteristic histopathologic features and HPV may not be detectable, requiring multiple histologic sections to avoid misdiagnosis 6
• Neurovascular hyperkeratosis (<1% of cases) is a rare variant where nerve endings and blood vessels become prominent, causing severe pain and bleeding with normal debridement—this mimics warts but represents chronic hyperkeratosis 2
• Biopsy is mandatory before aggressive treatment of any suspicious lesion that fails to respond to standard therapy, to exclude squamous cell carcinoma or other malignancy 1, 2
• In immunosuppressed patients, warts may be extensive and atypical, requiring lower threshold for biopsy 1