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Nevus Comedonicus Clinical Presentation

  • Author: Rossitza Lazova, MD; Chief Editor: William D James, MD  more...
Updated: Jun 27, 2016


The lesions are typically present at birth or develop in early childhood. They are usually asymptomatic. However, one case report described itching as an accompanying symptom. Patients usually seek help for cosmetic reasons. The lesions grow as the patient does and often grow faster at puberty. Patients may be able to express keratinaceous material from the pores.

With the inflammatory form, repeated bacterial infections, drainage, cysts, fistula and abscess formation, and scarring may develop.[7, 8, 9] Reports from 2015 and 2016 describe nevus comedonicus syndrome complicated by hidradenitis suppurativa‒like lesions.[10, 11]



The lesion appears as a collection of discrete, dilated follicular ostia plugged with pigmented keratinaceous material.[12, 13] They can be single or multiple, usually unilateral, and range in size from a few centimeters to involving half of the entire body.

Nevus comedonicus is typically found on the face, trunk, neck, and upper extremities.[14, 15, 16, 17] Rarely, it has been described on the palms[18] and soles, scalp,[19, 20] or penis.[21] When it occurs on the elbows and knees, it can appear as verrucous nodules.

Nevus comedonicus may be linear, interrupted, unilateral, bilateral, present in a dermatomal distribution, following the lines of Blaschko, or segmental.[9, 22, 23, 24, 25, 26, 27]

Nevus comedonicus syndrome is the association of nevus comedonicus with abnormalities in the central nervous system, skeletal system, skin, and eyes, as follows:

  • Central nervous system - Epilepsy, electroencephalogram abnormalities, transverse myelitis, microcephaly
  • Skeletal system - Scoliosis, hemivertebrae, spina bifida occulta, foot deformities, absent fifth finger, syndactyly, supernumerary digits
  • Skin - Ichthyosis, trichilemmal cysts, leukoderma, white hairs, Sturge-Weber syndrome, hemangiomas, linear basal cell nevus
  • Eye - Congenital cataracts (unilateral and bilateral)[28]
  • Other - Bilateral oligodontia,[29] multiple basal cell carcinomas, rare systemic malignancies


The cause is unknown. However, whole-exome sequencing in nevus comedonicus identified somatic NEK9 mutations, each affecting highly conserved residues within its kinase or RCC1 domains.[30] All mutations were gain of function, resulting in increased phosphorylation at Thr210, a hallmark of NEK9 kinase activation. The authors found that comedo formation in nevus comedonicus is marked by loss of follicular differentiation markers, expansion of keratin-15‒positive cells from localization within the bulge to the entire sub-bulge follicle and cyst, and ectopic expression of keratin 10, a marker of interfollicular differentiation not present in normal follicles. These findings suggest that NEK9 mutations in nevus comedonicus disrupt normal follicular differentiation and identify NEK9 as a potential regulator of follicular homeostasis.[30]



Persons with inflammatory nevus comedonicus can develop cysts, recurrent bacterial infections, fistulae, and abscesses, and these may subsequently heal with scarring. Treat these lesions with appropriate antibiotics or surgical drainage. Infections may be recurrent.

Contributor Information and Disclosures

Rossitza Lazova, MD Associate Professor of Dermatology and Pathology, Director of Dermatopathology Residency and Fellowship Program, Yale University School of Medicine; Consulting Pathologist/Dermatopathologist, Veterans Affairs Medical Center, West Haven, Connecticut

Rossitza Lazova, MD is a member of the following medical societies: American Academy of Dermatology, American Society of Dermatopathology, International Society of Dermatopathology

Disclosure: Nothing to disclose.

Specialty Editor Board

Michael J Wells, MD, FAAD Associate Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine

Michael J Wells, MD, FAAD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, Texas Medical Association

Disclosure: Nothing to disclose.

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

Barbara R Reed, MD Clinical Professor, Department of Dermatology, Dermatology Service, Denver Veterans Affairs Medical Center, University of Colorado Health Sciences Center; Consulting Staff, Denver Skin Clinic

Disclosure: Nothing to disclose.


The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous authors Joseph J. Shaffer, MBBS, Vincent A. de Leo, MD, to the development and writing of this article.

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