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Nongenital Warts Workup

  • Author: Philip D Shenefelt, MD, MS; Chief Editor: William D James, MD  more...
Updated: Feb 25, 2016

Laboratory Studies

The diagnosis of warts is made primarily on the basis of clinical findings. Immunohistochemical detection of HPV structural proteins may confirm the presence of virus in a lesion, but this has a low sensitivity. Viral DNA identification using Southern blot hybridization is a more sensitive and specific technique used to identify the specific HPV type present in tissue. Polymerase chain reaction may be used to amplify viral DNA for testing. Although HPV may be detected in younger lesions, it may not be present in older lesions.



Paring of warts may reveal minute black dots, which represent thrombosed capillaries. Obtain a biopsy if doubt exists regarding the diagnosis.


Histologic Findings

Common warts

Histopathologic features of common warts include digitated epidermal hyperplasia, acanthosis, papillomatosis, compact orthokeratosis, hypergranulosis, dilated tortuous capillaries within the dermal papillae, and vertical tiers of parakeratotic cells with entrapped red blood cells above the tips of the digitations. Elongated rete ridges may point radially toward the center of the lesion. In the granular layer, HPV-infected cells may have coarse keratohyaline granules and vacuoles surrounding wrinkled-appearing nuclei. Koilocytic (vacuolated) cells are pathognomonic for warts.

Deep palmoplantar warts (myrmecia)

Deep palmoplantar warts appear similar to common warts except that most of the lesion lies deep to the plane of the skin surface. This endophytic epidermal growth often has the distinctive feature of polygonal, refractile-appearing, eosinophilic, cytoplasmic inclusions composed of keratin filaments, forming ringlike structures. Basophilic nuclear inclusions and basophilic parakeratotic cells loaded with virions may be in the upper layers of the epidermis.

Flat warts

Flat warts resemble common warts on light microscopy; however, the features tend to be muted. Cells with prominent perinuclear vacuolization around pyknotic, strongly basophilic, centrally located nuclei may be in the granular layer. These may be referred to as "owl's eye cells."

Butcher's warts

Butcher's warts have prominent acanthosis, hyperkeratosis, and papillomatosis. Small vacuolized cells with centrally located shrunken nuclei may be seen in clusters within the granular layer rete ridges.

Filiform warts

Filiform warts may appear similar to common warts but tend to have prominent papillomatosis.

Focal epithelial hyperplasia (Heck disease)

Focal epithelial hyperplasia is characterized by a hyperplastic mucosa with thin parakeratotic stratum corneum, acanthosis, blunting and anastomosis of rete ridges, and pallor of epidermal cells as a result of intracellular edema. Some areas may have prominent keratohyaline granules, and some vacuolated cells may be present.

Cystic warts

A cyst filled with horny material characterizes cystic warts. The wall is composed of basal, squamous, and granular cells. Many of the epithelial cells may have large nuclei and clear cytoplasm with eosinophilic inclusion bodies. The cyst may rupture, resulting in a foreign body granuloma.

Contributor Information and Disclosures

Philip D Shenefelt, MD, MS Professor, Department of Dermatology and Cutaneous Surgery, University of South Florida College of Medicine; Past Chief, Section of Dermatology, James A Haley Veteran Affairs Medical Center

Philip D Shenefelt, MD, MS is a member of the following medical societies: American Academy of Dermatology, Florida Medical Association, Noah Worcester Dermatological Society, Society for Clinical and Experimental Hypnosis, American Contact Dermatitis Society, American Association for Physician Leadership, American Medical Association, American Society of Clinical Hypnosis

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Lester F Libow, MD Dermatopathologist, South Texas Dermatopathology Laboratory

Lester F Libow, MD is a member of the following medical societies: American Academy of Dermatology, American Society of Dermatopathology, Texas Medical Association

Disclosure: Nothing to disclose.

Chief Editor

William D James, MD Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine

William D James, MD is a member of the following medical societies: American Academy of Dermatology, Society for Investigative Dermatology

Disclosure: Nothing to disclose.

Additional Contributors

Joshua A Zeichner, MD Assistant Professor, Director of Cosmetic and Clinical Research, Mount Sinai School of Medicine; Chief of Dermatology, Institute for Family Health at North General

Joshua A Zeichner, MD is a member of the following medical societies: American Academy of Dermatology, National Psoriasis Foundation

Disclosure: Received consulting fee from Valeant for consulting; Received grant/research funds from Medicis for other; Received consulting fee from Galderma for consulting; Received consulting fee from Promius for consulting; Received consulting fee from Pharmaderm for consulting; Received consulting fee from Onset for consulting.


The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous author, Margaret H. Rinker, MD, to the development and writing of this article.

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Plantar warts.
Common wart on the hand.
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