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Nevus Comedonicus, a Rare Case: Dermoscopic and

Histopathological Findings

Adniana Nareswari

, Mardiana

, Nugrohoaji Dharmawan

, Oyong

Dermatovenereology Department Medical Faculty of Sebelas Maret University/ Dr. Moewardi General Hospital,

Surakarta, Indonesia

Pathology Anatomy Department Medical Faculty of Sebelas Maret University/ Dr. Moewardi General Hospital,

Surakarta, Indonesia

Keywords: Nevus, nevus comedonicus, adnexal hamartoma.

Abstract: Nevus comedonicus is a very rare adnexal hamartoma of pilosebaceous apparatus, with approximately 200

cases reported in the literature so far. It appears as cluster of adjacent dillated follicular openings with firm

pigmented keratin plugs resembling comedones. The comedones oftentimes arranged in linear or

zosteriform pattern, paralled to Blaschko’s lines. The lesions are commonly unilateral, although bilateral

occurence have been reported. The predilection sites are face, neck, upper arms, chest and abdomen. We

report a case of a 5-year-old boy with open brown to black comedones in a linear pattern localized on the

back of the left thigh that appearing since birth. The lesions gradually increased in number and size. The

plugs were firm and difficult to be extracted mechanically, leaving a big pore on the skin. Pain, itch and

discharge were not obtain. There were some episodes of infection, due to manual removal done by his

mother which left some hypertrophic scars. The patient was otherwise healthy, without any congenital

abnormalities, extracutaneous lesion, and internal involvement. Dermoscopic examination revealed the

distinctive pattern consisting of pigmented, sharply demarcated keratin plugs of 1-3 mm in diameter, some

open pores, multiple structurless, various shades of brown homogenous circular areas surrounding the plugs.

Punch biopsy of the lesion histologically showed an aggregation of dilated follicular infundibulum with

laminated keratinous material plugging. The follicular walls were comprised of several keratinocyte layers.

Based on the history taking, typical features of the lesion, dermoscopic and histopathological findings, this

patient was then diagnosed with nevus comedonicus.

1 INTRODUCTION

Nevus comedonicus is an extremely rare

developmental abnormality of the pilosebaceous

unit, which presenting as a constellation of dilated

follicular orifices filled with dark keratinous plugs.

It was first described as ‘comedo nevus’

(Kofmann,1895).

Its prevalence has been estimated

from 1 in 45,000 to 1 in 100,000, affecting any race

and gender (Kaliyadan,2017).

Retrospective study

conducted in Mexico City from 1971 to 2001,

among 417,511 paediatric patients , 443 displayed

epidermal naevi, but only 5 of them diagnosed as

nevus comedonicus (Vidaurri,2004). In Indonesia

itseft, there is no data on nevus comedonicus

prevalence.

The diagnosis of nevus comedonicus is relatively

easy. It has a typical and different feature compared

to other epidermal nevi. Dermoscopy, a safe non-

invasive easy-to-repeat diagnostic method mainly

used in melanocytic lesion helps in establishing the

diagnosis of nevus comedonicus (Winciorek,2011).

However the use of this tool is rare, and only a few

reports has been published regarding its use. A

typical histopathological feature confirms the

diagnosis in uncertain case.

This study aimed to present a rare case of nevus

comedonicus with regard to its clinical,

dermoscopic, histopathological features and the use

of dermoscopy in this rare condition.

2 CASE

A 5-year-old Indonesian boy presented to our

outpatients clinic, Dermatovenereology Department,

Nareswari, A., Mardiana, ., Dharmawan, N. and Oyong, .

Nevus Comedonicus, a Rare Case: Dermoscopic and Histopathological Findings.

DOI: 10.5220/0008160204810484

In Proceedings of the 23rd Regional Conference of Dermatology (RCD 2018), pages 481-484

ISBN: 978-989-758-494-7

481

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dr. Moewardi General Hospital, Surakarta, Indonesia

for evaluation of open brown to black, firm and

protude comedones, localized to the back of his left

thigh in a linear pattern along Blaschko’s lines

(Figure 1), which has occured since birth. His

mother reported that the lessions gradually increased

in number and size with time. The patient ever been

evaluated in our hospital when he was 1 month old.

At that time he received various topical treatments

but there was no satisfactory improvement.

The parents took him again to our outpatient

clinic after years due to their concern about this

asymptomatic lesion which became increased in

number and size. There were no complaints of pain,

itch and discharge. His mother tried to remove the

plugs herself which left a big pore on the skin and

caused some episodes of infections. Though it

healed, it left some hypertrophic scars. Medical

history was unremarkable with no similiar complaint

in his family. The parents denied for consanguity.

Pregnancy and labor were uneventful. The mother

also denied for any drug consumption during

pregnancy.

Clinical examination on his back of the left thigh

revealed multiple, comedo-like openings with brown

to black, firm keratin plugs dispersed over a

hypopigmented, linear spot of 20 cm x 4 cm, with

some hypertrophic scars on it. His vital signs, body

weight and height were normal for his age. There

was no other cutaneous findings on the other part of

body.

Ophthalmological and neurological examinations

did not reveal any abnormality. Laboratory findings

(complete blood count, liver functions and kidney

functions) were unremarkable. The dermoscopic

revealed the distinctive pattern consisting of

pigmented, sharply demarcated keratin plugs of 1-3

mm in diameter, some open pores, multiple

structurless, various shades of brown homogenous

circular areas surrounding the plugs (Figure 2A). A

3 mm punch biopsy was obtained from his back of

the left thigh. Histopathological examination

showed an aggregation of dilated follicular

infundibulum with laminated keratinous material

plugging. The follicular walls were comprised of

several layers of keratinocytes. Epidermis was

within normal limit (Figure 2B). This patient was

diagnosed with nevus comedonicus based on the

history taking, clinical examination which pictured

the typical lesion of nevus comedonicus,

dermoscopic and histopathological finding.

3 DISCUSSION

Nevus comedonicus is an extremely rare

dermatological problem with an estimated

occurrence of 1 case in every 45,000–100,000

individuals (Kaliyadan,2017). A study by Inoue et

al., reported that there were only 200 cases until the

year of 2000 (Inoue,2000). A retrospective study

conducted in Mexico City from 1971 to 2001,

among 417,511 paediatric patients , 443 displayed

epidermal naevi, but only 5 of them diagnosed as

nevus comedonicus (Vidauri,2004).

There has not

been any data about the prevalence or even the case

report of nevus comedonicus in Indonesia so far.

Figure 1. Nevus comedonius on the back and left thigh. A

cluster of firm, pigmented, protrude comedo-like papules

in a linear pattern along Blaschko’s line.

Figure 2. A: Dermoscopy of nevus comedonicus. Multiple

dillated follicular openings (red arrow) with pigmented

keratin plugs 1-3 mm in diameter (blue arrow) and

structurless, various shades of brown homogenous circular

areas surrounding the plugs (black arrow). B:

Histopathology of nevus comedonicus. Laminated

keratinous material plugging on dermis and epidermis

within normal limit. The follicular walls are comprised of

several keratinocyte layers.

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Approximately 50% of nevus comedonicus cases

appear at birth, with the other 50% developed

symptoms during childhood, usually before the age

of 10 years. There is no predilection for race or

gender (Pierson,2003).

Clinically, nevus comedonicus present as a

collection of discrete, dilated follicular ostia plugged

with horny brown to black pigmented keratin. The

lesions are most commonly found on face, neck,

upper arms, chest and abdomen, usually arranged in

groups, bands, or in a linear pattern along

Blaschko’s lines (Solomon,1975).

Normally it is

unilateral but can be bilateral in certain case

(Mahran,2017).

Nevus comedonicus is classified

into two groups, reflecting the severity of the

condition: the first group is characterized by the

presence of slightly pronounced skin lesions or

comedo-like changes, which represent only a

cosmetic defect, the second one presents with severe

cutaneous symptoms including large cysts with

scarring, often with a tendency to recurrence with

the formation of fistulas and abscesses

(Guldbakke,2007).

Nevus comedonicus in unusual

cases, may appear as an extensive inflammatory

lesion involving large areas of the body, with

inflammation and residual scarring (Kirtak,2004).

Several disorders have been known to be

associated with nevus comedonicus. Cases showing

any of these findings are included in nevus

comedonicus syndrome, an entity considered within

the larger group of epidermal nevus syndrome.

Nevus comedonicus syndrome is characterized as a

combination of nevus comedonicus with ocular

defect (cataracs, corneal erosion), skeletal defect

(syndactily, clinodactily, preaxial polydactily,

absence of a ray of hand bones, scoliosis, vertebral

defects) and neurologic defect (microcephaly,

mental deficiency, dysgenesis of corpus callosum)

(Happle,2010). In our patient, the nevus

comedonicus present alone without any other

cutaneous or extracutaneous lesion and also no

abnormalities found in ophtalmological and

neurological examination.

In our patient, the dermoscopic examination

revealed the distinctive pattern consisting of dark,

sharply demarcated keratin plugs of 1-3 mm in

diameter, some open pores, numerous structurless,

circular and barrel shaped, homogenous areas with

hyperkeratotic plugs of various shades of brown.

These features were suggestive of nevus

comedonicus. Winciorek and Spiewak defined

dermoscopic features of nevus comedonicus as

numerous circular and barrel-shaped homogenous

areas in light and dark-brown shades with

remarkable keratin plugs (Winciorek,2013).

Dermoscopy as a diagnostic tool is safe, non-

invasive and easy-to-repeat prosedure which is

mainly used in melanocytic lesion. Its also helpful in

diagnosing nevus comedonicus (Winciorek,2011).

However, the use of this diagnostic tool has not been

widely applied, only two reports have been

published (Winciorek,2013) (Vora,2017).

Dermoscopy is useful in differentiating nevus

comedonicus from comedones of acne and other rare

epidermal nevi, such as sebaceous nevus and hair

follicle nevus. Comedones of acne vulgaris show

numerous, homogenous areas, light and dark-brown,

sometimes black in color, depending on the type of

acne, open or closed comedones, predominantly

circular and situated superficially on dermoscopy.

Sebaceous nevus shows bright, yellow spot which

are not associated with hair follicles. Many follicular

openings and interfollicular “pseudo-pigment

network” on dermoscopy characterized hair follicle

nevus (Okada,2008).

Histopathological examination of nevus

comedonicus demonstrate a wide, deep invagination

of the epidermis filled with keratin. These

invaginations resemble dilated hair follicle; in fact,

as evidence that they actually represent rudimentary

hair follicles, occasionally found in the lower

portion of an invagination one or even several hair

shafts (Elder,2009). These similiar with histological

findings of our patient. Histologically it is important

to differentiate it with comedonal acne. In

comedonal acne, the pilosebaceous units are

complete whereas those in nevus comedonicus are

poorly formed. Furthermore in nevus comedonicus,

hyperkeratosis and papillomatosis are frequently

seen in the interpapillary epidermis and absent in

comedonal acne. Dilated pore of Winer can

sometimes be confused with nevus comedonicus

histologically. However, this condition is usually

observed in the elderly and can be differentiated

clinically.

Clinical findings themself can be used to

establish the diagnosis of nevus comedonicus as the

diagnosis of nevus comedonicus is predominantly

clinical. The differentiation of nevus comedonicus

from other epidermal nevi is easy as the former

shows presence of “comedones”, which on

extraction will leave a big pore on the skin surface.

The finding of groups of lesions paralleled to

Blascko’s lines ruled out comedonal acne. In the

majority of cases, dermoscopy may prove helpful

while biopsy is only indicated in uncertain cases.

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4 CONCLUSION

Diagnosing nevus comedonicus is relatively easy,

however clinician should be aware of the potential

association of nevus comedonicus with other

cutaneous lesion and extracutaneous features, such

as occular, skeletal and neurologic abnormalities as

nevus comedonicus syndrome. Furthermore, our

case report shows a typical feature and dermoscopic

findings of nevus comedonicus wich is rarely

described in literature. This case report also prove

that dermoscopy examination, a simple non-invasive

diagnostic tool is very helpful in diagnosing nevus

comedonicus. We recommend this tool to

differentiate the diagnosis of other rare epidermal

nevi, such as sebaceous nevus and hair follicle nevus

while histopathological examination should be

performed only in uncertain cases.

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