Skin nontumor

Infectious disorders

Warts (verrucae)

Topic Completed: 7 June 2021

Minor changes: 19 July 2021

Copyright: 2002-2021,, Inc.

PubMed Search: Warts[title] skin[title] pathology

Heba Ahmed Abdelkader, M.D.
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Cite this page: Abdelkader, H, Elbendary A. Warts (verrucae). website. Accessed September 20th, 2021.
Definition / general
Essential features
  • Verrruca vulgaris: common wart
  • Condyloma acuminata: genital warts
  • Verruca palmaris / verruca plantaris: palmar / plantar warts
  • Myrmecia: special type of plantar wart
  • Verrucae planae: Plane warts
ICD coding
  • ICD-10: B07 - Viral warts
  • ICD-10: B07.9 - Viral wart, unspecified
  • 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
  • HPV integrates low / high grade squamous intraepithelial lesions (SIL) within the host DNA
  • Anogenital HPV infection integrates within the host DNA → intraepithelial neoplasia → low / high grade squamous intraepithelial lesions (SIL) Clin Colon Rectal Surg 2019;32:347
Clinical features
  • Common warts: hyperkeratotic flesh colored papules with pinpoint black dots (thrombosed capillaries) (J Dtsch Dermatol Ges 2019;17:613)
  • Palmar / plantar warts: thick, deep endophytic papules with black dots (J Dtsch Dermatol Ges 2019;17:613)
  • Flat / plane warts: light pink-brown, flat topped papules (J Dtsch Dermatol Ges 2019;17:613)
  • Genital warts: smooth, sessile, raised, skin colored to brown lobulated papules (Infect Dis Clin North Am 2013;27:765)
  • Recurrent respiratory papillomatosis: nonspecific symptoms of airway involvement (chronic cough, hoarseness, wheezing, voice change, stridor and chronic dyspnea) (Respir Med 2017;126:116)
  • Genetic syndromes:
    • Epidermodysplasia verruciformis: increased susceptibility to genus β HPV types
      • Generalized polymorphic papules (flat wart-like appearance on the dorsal hands, neck, face and extremities)
      • Scaly, pink macules, hypopigmented, guttate macules / patches and seborrheic keratosis-like lesions on forehead, neck, trunk (Front Microbiol 2018;9:1222)
    • WHIM syndrome: a rare primary immunodeficiency disorder characterized by warts, hypogammaglobinemia, infections and myelokathexis (Expert Opin Orphan Drugs 2017;5:813)
    • WILD syndrome: warts, immunodeficiency, lymphedema and dysplasia (anogenital) (Expert Opin Orphan Drugs 2017;5:813)
Prognostic factors
Case reports
Clinical images

Contributed by Heba Ahmed Abdelkader, M.D.

Verrucae vulgaris

Images hosted on other servers:

Giant condyloma acuminatum

Tattoo associated flat warts

Epidermodysplasia verruciformis

Verruca plantaris

Gross description
  • Flesh colored or brown papules or plaques with rough surface
  • Single or multiple
  • Recurrent respiratory papillomatosis: sessile or pedunculated soft exophytic nodules in the larynx or nasopharynx, tracheobronchial tree and pulmonary parenchyma
  • 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
    • Vacuolated superficial keratinocytes with pyknotic raisin-like nuclei (koilocytes)
    • Koilocytes are not seen in older lesions
    • 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
  • 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
  • Epidermodysplasia verruciformis (Arch Pathol Lab Med 2018;142:700):
    • Acanthosis with small nests of large cells with pale blue-gray cytoplasm, clear nuclei and perinuclear halos
    • May evolve to squamous cell carcinoma
  • Recurrent respiratory papillomatosis (Mayo Clin Proc 2017;92:322):
    • True papillae lined with hyperplastic squamous epithelium containing koilocytes
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

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:
      • 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 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 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 HHV presents as painful grouped vesicles on an erythematous base. D is incorrect, as MCV presents with white umbilicated papules.

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Reference: Warts
Board review style question #2
Which of the following histopathologic features favors a diagnosis of a wart?

  1. Acanthosis
  2. Basal layer vacuolation
  3. Hyperkeratosis
  4. Koilocytic change
Board review style answer #2
D. Koilocytic change. Koilocytes represent the characteristic histopathologic finding in warts. 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.

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Reference: Warts
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