You are in: eMedicine Specialties > Dermatology > BENIGN NEOPLASMS Nevus ComedonicusArticle Last Updated: Mar 13, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: 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 is a member of the following medical societies: American Academy of Dermatology, American Society of Dermatopathology, and International Society of Dermatopathology Editors: Barbara Reed, MD, Clinical Associate Professor, Department of Dermatology, Dermatology Service, Denver Veterans Administration Hospital, University of Colorado Health Sciences Center; Consulting Staff, Denver Skin Clinic; Michael J Wells, MD, Associate Professor, Department of Dermatology, Texas Tech University Health Sciences Center; Lester F Libow, MD, Dermatopathologist, South Texas Dermatopathology Laboratory; Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University; Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center Author and Editor Disclosure Synonyms and related keywords: comedone nevus, nevus acneiformis unilateralis, nevus follicularis keratosus, nevus unilateralis comedonicus, nevus zoniforme INTRODUCTIONSection 2 of 10
  BackgroundIn 1895, Kofmann1 described the first case of nevus comedonicus (NC). It manifests as groups of closely set, dilated follicular openings with dark keratin plugs resembling comedones. The majority of cases are isolated. However, NC may be part of NC syndrome in association with skeletal or central nervous system anomalies, ocular abnormalities, and cutaneous defects. PathophysiologyMany consider NC to be a hamartoma deriving from a failure of the mesodermal part of the folliculosebaceous unit to develop properly, with subsequent abnormal differentiation of the epithelial portion. The follicular structures that result are unable to form terminal hair or sebaceous glands and are capable only of producing soft keratin, which accumulates in the adnexal orifices and produces the comedonelike lesions observed in persons with this condition. Another view is that NC is an epidermal nevus involving hair follicles or an appendageal nevus of sweat ducts. Lesions that extend onto a palm or sole typically demonstrate sweat duct dilatation with keratin in the volar portion of the lesion. See Epidermal Nevus Syndrome for more information. The etiology of NC is unclear. Why some NC patients present late in life is not known, although a genetic mosaicism has been proposed. While the majority of cases are sporadic, several families with this condition have been documented. Only one report has described NC occurring in homozygous twins.2 FrequencyUnited StatesExact figures are lacking. NC is considered relatively rare. One dermatology department found 12 cases in 100,000 skin biopsy specimens. Another department reported an incidence of 1 case per 45,000 dermatology visits. The incidence of NC syndrome is even more difficult to estimate; it is considered less common than nonsyndromal NC. Mortality/MorbidityMost patients are asymptomatic. Uncommonly, the lesions become repeatedly inflamed and infected, leading to painful cysts, abscesses, fistula formation, and scarring. Additionally, patients may be distressed over the cosmetic appearance of the lesions. RaceNo racial predilection is recognized. SexMales and females are equally affected. AgeApproximately 50% of cases of NC are evident at birth, with the other 50% developing during childhood, usually before age 10 years. A few case reports describe onset later in life, including in the seventh decade. These cases usually occur after some form of trauma3 or a rash. CLINICALSection 3 of 10
HistoryThe 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. PhysicalThe lesion appears as a collection of discrete, dilated follicular ostia plugged with pigmented keratinaceous material. They can be single or multiple, usually unilateral, and range in size from a few centimeters to involving half of the entire body. NC is typically found on the face, trunk, neck, and upper extremities. Rarely, it has been described on the palms4 and soles or penis.5 When it occurs on the elbows and knees, it can appear as verrucous nodules. NC may be linear, interrupted, unilateral, bilateral, present in a dermatomal distribution, following the lines of Blaschko, or segmental. NC syndrome is the association of NC with abnormalities in the central nervous system, skeletal system, skin, and eyes, as follows:
CausesThe cause is unknown. DIFFERENTIALSSection 4 of 10
Acne Vulgaris Chloracne and acne conglobata with extensive comedones Epidermal nevus Familial dyskeratotic comedones Favre-Racouchot Syndrome (Nodular Elastosis with Cysts and Comedones) Keratosis Pilaris Lichen Striatus Nevus Sebaceus WORKUPSection 5 of 10
Lab StudiesMany cases have been reported in which extensive laboratory evaluation has yielded no abnormalities. No particular laboratory test is specifically indicated. Imaging StudiesPerform ProceduresSkin biopsy may be performed to confirm the diagnosis. Histologic FindingsTypically, closely positioned dilated follicular infundibula with prominent orthokeratotic plugging are present, sebaceous elements are rudimentary or absent, and mature hair follicles are absent. The follicular walls are lined by epithelium that often appears atrophic, and it is composed of a few layers of keratinocytes. Epithelial follicular budding may be seen. The interfollicular epidermis is often normal but may appear papillomatous or hyperkeratotic. No apocrine glands are seen. Several reports of NC show epidermolytic hyperkeratosis in the follicular epithelium. On volar surfaces, eccrine ducts are involved. TREATMENTSection 6 of 10
Medical CareAsymptomatic lesions may be left untreated or therapy may be implemented for cosmetic concerns. Some lesions improve with topical retinoic acid,6, 7 salicylic acid, or ammonium lactate lotion.8 Surgical CareDisfiguring lesions may require surgical interventions.9 ConsultationsIf defects associated with a NC syndrome are found, consult the appropriate specialist.
MEDICATIONSection 7 of 10
Both topical and oral therapies have been tried. Improvement may occur with the use of topical retinoic acid, salicylic acid, or ammonium lactate lotion. Isotretinoin (Accutane) is not usually recommended because of the long-term treatment requirement, but it may be beneficial in preventing cyst formation.
Drug Category: RetinoidsTopical retinoids are known to have effects on keratinocyte proliferation and differentiation. This is believed to loosen comedones and facilitate extraction.
Drug Category: Keratolytic agentsCause cornified epithelium to swell, soften, macerate, and then desquamate.
FOLLOW-UPSection 8 of 10
ComplicationsPersons with inflammatory NC 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. PrognosisSpontaneous resolution has not been described. All lesions persist unless treated. They often grow at puberty. ACKNOWLEDGMENTSSection 9 of 10
The authors and editors of eMedicine gratefully acknowledge the contributions of previous authors Joseph J. Shaffer, MBBS, Vincent A. de Leo, MD, to the development and writing of this article. Additionally, we gratefully acknowledge the contributions of previous Editor-in-Chief, William James, MD, to the development and writing of this article. REFERENCESSection 10 of 10
Article Last Updated: Mar 13, 2008 |
