Skin nontumor

Infectious disorders

Warts (verrucae)

Resident / Fellow Advisory Board: Caroline I.M. Underwood, M.D.
Editorial Board Member: Jonathan D. Ho, M.B.B.S., D.Sc.
Heba Ahmed Abdelkader, M.D.

Last author update: 7 June 2021
Last staff update: 17 April 2023

Copyright: 2002-2024,, Inc.

PubMed Search: Warts

Heba Ahmed Abdelkader, M.D.
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Cite this page: Abdelkader, H, Elbendary A. Warts (verrucae). website. Accessed February 26th, 2024.
Definition / general
Essential features
  • Verruca vulgaris: common wart
  • Condyloma acuminata: genital warts
  • Verruca palmaris / verruca plantaris: palmar / plantar warts
  • Myrmecia: special type of palmoplantar wart
  • Verrucae planae: Plane warts
ICD coding
  • ICD-10:
    • B07 - viral warts
    • B07.9 - viral wart, unspecified
  • ICD-11:
    • 1E80 - common warts
    • 1E81 - plane warts
    • 1E82 - warts of lips or oral cavity
    • 1E83 - wart virus proliferation in immune deficient states
    • 1E8Z - viral warts, not elsewhere classified
    • 1A95 - anogenital warts
  • Spread via direct contact (sexual, skin to skin / fomite)
  • HPV invades the epidermal basal cells through microabrasions; induces hyperplasia and hyperkeratosis
  • Most infections are cleared by immune response
  • Virus binding to the receptor → virus is internalized into the cell by endocytosis → viral genome enters the nucleus
  • E6 and E7 HPV proteins hijack the checkpoint mechanisms of the cell cycle → uncontrolled proliferation
  • Viral genome replication with increased levels of the E1, E2, E4 and E5 proteins
  • In the terminally differentiated layer of epithelium L1 and L2 capsid proteins are expressed and viral particles are assembled
  • The virions are sloughed off with the dead squamous cells of the host epithelium for further transmission (Front Biosci (Landmark Ed) 2018;23:1587)
Clinical features
Prognostic factors
Case reports
Clinical images

Contributed by Heba Ahmed Abdelkader, M.D.

Verrucae vulgaris

Images hosted on other servers:

Tattoo associated flat warts

Epidermodysplasia verruciformis

Verruca plantaris

Gross description
  • Flesh colored or brown papules or plaques with rough surface
  • Single or multiple
  • See also: clinical features
Gross images
Microscopic (histologic) description
  • Common warts (verruca vulgaris) (Arch Pathol Lab Med 2018;142:700):
    • Hyperkeratosis, papillomatosis, hypergranulosis
    • Columns of parakeratosis, especially over projecting dermal papillae
    • Intracorneal hemorrhage
    • Vacuolated superficial keratinocytes with pyknotic raisin-like nuclei (koilocytes)
    • Koilocytes may not be seen in older lesions
    • Koilocytes are not needed for the diagnosis
    • Inward bending of rete ridges at borders of lesion (toeing in)
    • Dilated capillaries in dermal papillae
    • Projects above the plane of the epidermis
  • Palmar / plantar warts (verruca palmaris and verruca plantaris) (Arch Pathol Lab Med 2018;142:700):
    • Similar to verruca vulgaris (clinical distinction based on location)
    • Endophytic growth - greater proportion of the lesion lies beneath the plane of the epidermis
  • Myrmecia warts (J Cutan Pathol 2012;39:936):
    • Marked acanthosis
    • Large eosinophilic intracytoplasmic inclusion bodies
  • Plane warts (verrucae planae) (Arch Pathol Lab Med 2018;142:700):
    • Acanthosis and hyperkeratosis
    • No papillomatosis or parakeratosis
    • Vacuolization of the cells of the upper stratum spinosum and stratum granulosum with margination of keratohyalin granules
    • Often have dyskeratotic keratinocytes
  • Condyloma acuminatum (venereal / genital warts) (Head Neck Pathol 2019;13:80):
    • More massive acanthosis with bulbous rete ridges (condyloma means fist or knuckle)
    • Koilocytes in the upper spinous layer
    • Parakeratosis ofen in the valleys of the epithelium (crypt parakeratosis) (see condyloma)
  • Epidermodysplasia verruciformis (Arch Pathol Lab Med 2018;142:700):
    • Hyperkeratosis and hypergranulosis
    • Acanthosis with small nests of large cells with pale blue-gray cytoplasm, clear nuclei and perinuclear halos
    • May evolve to squamous cell carcinoma
Microscopic (histologic) images

Contributed by Heba Ahmed Abdelkader, M.D.

Verrucae vulgaris


Myrmecia wart

Myrmecia inclusion bodies

Contributed by Hillary Rose Elwood, M.D. and AFIP images
Verruca vulgaris Verruca vulgaris Verruca vulgaris

Verruca vulgaris

Condyloma accuminatum

Contributed by @MirunaPopescu13 on Twitter
Warts (verrucae) Warts (verrucae)

Warts (verrucae)

Positive stains
Electron microscopy description
Molecular / cytogenetics description
  • HPV: in situ hybridization
Molecular / cytogenetics images

Images hosted on other servers:

HPV16 integration patterns



Verruca vulgaris

Epidermodysplasia verruciformis (EDV)

Respiratory papillomatosis (squamous papilloma)

Sample pathology report
  • Skin papule, dorsal left foot, punch biopsy:
    • Histopathological features are consistent with verruca vulgaris (see comment)
    • Comment: The epidermis showed hyperkeratosis, papillomatosis, hypergranulosis and columns of parakeratosis over projecting dermal papillae. Dilated capillaries were seen in the dermal papillae. Rete ridges showed inward bending at the borders of the lesion. Vacuolated superficial keratinocytes with pyknotic raisin-like nuclei (koilocytes) were seen.
Differential diagnosis
  • Verruca vulgaris:
    • Seborrheic keratosis:
      • Variable combinations of hyperkeratosis, papillomatosis, acanthosis
      • Horn pseudocysts
      • No hypergranulosis, koilocytes or tiers of parakeratosis
    • Epidermal nevus:
      • Hyperkeratosis, papillomatosis, acanthosis
      • No koilocytes or tiers of parakeratosis
    • Acrochordon:
      • Pedunculated papule, epidermis often extends almost completely around a fibrovascular core
      • Papillomatosis and acanthosis
      • No koilocytes or tiers of parakeratosis
    • Acanthosis nigricans:
      • Lesser degree of hyperkeratosis and papillomatosis
      • Acanthosis minimal or absent
      • Basal layer hyperpigmentation
      • No koilocytes or tiers of parakeratosis
  • Myrmecia:
    • Molluscum contagiosum:
      • Crater filled with eosinophilic to basophilic intracytoplasmic inclusions (Henderson-Patterson bodies) that push the nucleus and numerous keratohyaline granules aside
  • Condyloma acuminata:
    • Bowenoid papulosis:
      • Atypical keratinocytes throughout the full thickness of the epidermis with several mitoses in metaphase
    • Verrucous carcinoma:
      • Well differentiated SCC with pushing invasive border
      • More mitoses and mild cytologic atypia
    • Condyloma lata:
      • More moist than condylomata acuminata and may be ulcerated.
      • Acanthosis with neutrophils in the epidermis
      • Perivascular plasma cell infiltrate
      • Spirochetes on dark field examination (and IHC) and reactive syphilis serology
Board review style question #1

A 9 year old boy presents with multiple flesh colored skin papules on his hand. A skin biopsy of one of the lesions is shown. Which of the following is the most likely cause of his condition?

  1. Cytomegalovirus (CMV)
  2. Human herpesvirus type 1 (HHV1)
  3. Human papillomavirus type 1 (HPV1)
  4. Molluscum contagiosum virus type 1 (MCV1)
Board review style answer #1
C. Human papillomavirus type 1 (HPV1). HPV is the cause of verrucae vulgaris which presents as flesh colored papules, especially on the hands and feet. A is incorrect because CMV infection presents with fever, pneumonitis, hepatitis, encephalitis, chorioretinitis, gastroenteritis and a wide variety of skin manifestations, including morbilliform eruption, blueberry muffin rash in babies and ulcers. B is incorrect because 1 (Herpes simplex virus 1) presents as painful grouped vesicles on an erythematous base. D is incorrect, as MCV presents with umbilicated papules.

Comment Here

Reference: Warts
Board review style question #2
Which of the following histopathologic features is most specific for a diagnosis of verruca vulgaris?

  1. Acanthosis
  2. Basal layer vacuolation
  3. Hyperkeratosis
  4. Koilocytic change
Board review style answer #2
D. Koilocytic change. Koilocytes represent the characteristic viral cytopathic change seen in verruca vulgaris. While their presence is not required for diagnosis, when identified, they definitively implicate HPV. They are vacuolated keratinocytes with pyknotic raisin-like nuclei in the superficial layers of the epidermis. A and C are nonspecific findings that can occur in many other diseases. B is incorrect, as basal layer vaculoation is not seen in warts.

Comment Here

Reference: Warts
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