Onychomatricoma

Abstract

Onychomatricoma is a benign neoplasia that occurs specifically in the nail apparatus. It was described in 1992, and is the only tumor in which the change of the nail plate is actively caused by the lesion. It lies in the nail matrix,and has fingerlike projections that are embedded in the nail plate, resulting in thickening, longitudinal grooves, yellow discoloration and splinter hemorrhages. Although described as a rare tumor, it is believed to be underdiagnosed. The present study is aimed at reviewing onychomatricoma's clinical features as well as the complementary examinations that are used to recognize and diagnose this tumor.

Full text

Authors:
Nilton Di Chiacchio1
Glaysson Tassara Tavares2
Emerson Henrique Padoveze3
Diego Leonardo Bet4
Nilton Gioia Di Chiacchio5
1PhD in Dermatology, Head of the
Dermatology Department of the Hospital
do Servidor Público Municipal de São
Paulo—São Paulo (SP), Brazil
2Volunteer Physician at the Dermatology
Medical Residency of the Hospital Central
da Universidade Federal de Minas Gerais
(UFMG)—Belo Horizonte (MG), Brazil
3Assistant Physician at the Dermatology
Clinic of the Hospital do Servidor Público
Municipal de São Paulo
4Volunteer Assistant Physician at the
Dermatology Clinic of the Hospital do
Servidor Público Municipal de São Paulo
5Intern Physician at the Micrographic
Surgery Service of the Dermatology Clinic
of the Hospital do Servidor Público
Municipal de São Paulo
Correspondence:
Dr. Nilton Di Chiacchio
Rua Machado Pedrosa, 370—Jardim São
Paulo
Cep: 02045-010 - São Paulo—SP, Brazil
E-mail: ndchia@terra.com.br
Received on: 27 February 2013
Approved on: 15 March 2013
The present study was carried out at the
Hospital do Servidor Público Municipal de
São Paulo—São Paulo (SP), Brazil.
Financial support: None
Conflict of interest: None
Surg Cosmet Dermatol 2013;5(1):104.
Onychomatricoma
Onychomatricoma
ABSTRACT
Onychomatricoma is a benign neoplasia that occurs specifically in the nail apparatus. It was described in 1992,
and is the only tumor in which the change of the nail plate is actively caused by the lesion. It lies in the nail
matrix,and has fingerlike projections that are embedded in the nail plate, resulting in thickening, longitudinal
grooves, yellow discoloration and splinter hemorrhages. Although described as a rare tumor, it is believed to be
underdiagnosed. The present study is aimed at reviewing onychomatricoma’s clinical features as well as the
complementary examinations that are used to recognize and diagnose this tumor.
Keywords: nail diseases; nails/pathology; neoplasms.
RESU MO
Onicomatricoma é neoplasia benigna específica do complexo ungueal descrita em 1992,
sendo o único tumor em que a alteração da placa ungueal é produzida ativamente pela
lesão. Encontra-se na matriz ungueal apresentando projeções digitiformes que ficam
impressas na placa ungueal, resultando em espessamento, estrias longitudinais, coloração
amarelada e hemorragias em estilhaço. Apesar de descrito como tumor raro acredita-se
que seja subdiagnosticado. O objetivo deste artigo é revisar as características clínicas e os
exames complementares subsidiários para o reconhecimento e diagnóstico desse tumor.
Palavras-chave: doença das unhas; unhas/patologia; neoplasias.
10
INTRODUCTION
Onychomatricoma (OM) is a benign tumor arising from the
nail matrix. It was first described by Baran and Kint in 1992 1as the
first onychomatrixoma. In 1995, Hanekee and Fränken, based on
histological aspects, proposed the term onychomatricoma, which
has been used since then. 2Also, on a histological basis, other quo-
tes and nomenclature, such as onychoblastoma, onychoblastic fibro-
ma and atypical onychoblastic fibroma are currently found, howe-
ver the term onychomatricoma remains the most frequently used
and cited in the current literature. 3, 4
It is considered a rare and specific tumor of the nail apparatus,
characterized by the presentation of fingerlike projections from the
matrix, and is the only tumor in which alterations of the nail plate
are actively produced by the lesion. 2,5
Since its first description, just over 40 cases have been repor-
ted. Although considered a rare condition, its clinical, radiological,
dermoscopic, histological, and electron microscopy-based aspects
have been well documented. Recent studies consider the tumor’s
Continuing
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Onicomatricoma 11
diagnoses include subungual exostosis, fibrokeratoma, fibroma, ony-
chomycosis, epidermoid carcinoma, Bowen's disease, keratoacant-
homa, verruca vulgaris, acral superficial fibromyxoma, melanoma,
bacterial infections, dermatofibrosarcoma protuberans, porocarci-
noma, andosteochondroma. 4
Onychomycosis has been implicated as a predisposing factor
for the emergence of onychomatricoma (reactive theory of the
lesion). On the other hand, onychomatricoma can also be conside-
red a predisposing factor for onychomycosis 9,15
DIAGNOSIS
In addition to the classic tetrad of signs, other methods such
as dermoscopy of the nail plate,16 ultrasound 17,18 MRI 19 ungual clip-
ping, 20 and histologic study, 7,13,21 can be employed to aid in the
diagnosis of onychomatricoma. (Figures 1 and 2)
The dermoscopy of the nail plate evidences perforations in
the distal portion of the ungual plate,16 hemorrhagic striae, and
white longitudinal grooves corresponding to the nail plate chan-
nels. 5(Figure 3)
Radiologically, there is no bone involvement linked to ony-
chomatricoma. 20
Ultrasound has been shown useful in the tumor’s detection,
delimitation, and topography. For a good view of the lesion at this
body site, the device’s frequency should be set at seven to 15 MHz.
The tumor is seen as a hypoechogenic area affecting the nail matrix
and a hyperechogenic area corresponding to the fingerlike projec-
tions, in addition to having a low blood flow. 18
With MRI, the tumor is easily seen in the sagittal cuts, affec-
ting the nail matrix, with low signal capture, and resembling nor-
mal epidermis. At the distal section, the digitations are observed
with high signal capture, as the mucoid stroma present in the area
of the tumor has a high concentration of water (T2). The axial cuts
allow the viewing of perforations in the nail plate. 19
Nail clipping is the histologic study of the nail plate in which
the analyzed specimen is removed by cutting the distal part of the
Surg Cosmet Dermatol 2013;5(1):104.
FIGURE 1: A)Thickening, yellowish color, longitudinal striation and small splinter hemorrhages in the nail plate (black arrow); b) longitudinal section;
c) MRI crosssection showing a lesion with fingerlike projections (red arrows); d) tumor seen intraoperatively; e) bottom view; f) posterior view of the
onychomatricoma’s pathognomonic digitations impressions of the nail plate.
genetic alterations, such as losses on chromosome 11. 4Its slow
growth and the absence of pain in most cases explain patients’ typi-
cal delay in seeking medical attention.
ETIOPATHOGENESIS
Although onychomatricoma’s etiology is still not fully unders-
tood, trauma is considered the main predisposing factor. Another
hypothesis is that it corresponds to a reactive picture and not to a
matrix tumor. 2Some authors suggest that onychomatricoma is an
epithelial and conjunctive tissue hamartoma that mimics the nail
matrix’s structures. 1,6,7
CLINICAL PICTURE
Onychomatricoma affects mainly females (2,16:1), with the
peak of incidence around the age of 51. 8It rarely affects children,
with only one case described in the literature. 9Despite its preva-
lence in Caucasians, there are reports of involvement of other eth-
nicities 10 and one case described in a patient of African heritage.
11 It rarely causes pain and fingers are more affected than toes—
this information is biased however, since there is greater patient
concern and demand for a doctor’s intervention for lesions that
affect fingers. 4
Onychomatricoma classically manifests with the clinical
tetrad: (1) yellowish longitudinal band of variable thickness, (2)
splinter hemorrhages preferentially affecting the proximal portion
of the nail plate, (3) longitudinal and transverse hypercurvature of
the nail plate, and (4) fingerlike projections that emerge from the
nail matrix, leaving cavities in the nail plate. 12 (Figure 1)
Due to the fact that it is a matrix tumor, a nodule can be cli-
nically observed in the proximal nail fold. Besides the clinical tetrad,
onychomatricoma can present as longitudinal melanonychia
(hypermelanosis), nail dystrophy, subungual hematoma, verrucous
aspect in the proximal nail fold, dorsal pterygium, giant variant and
normal type of pseudo-fibrokeratoma, in addition to the resem-
blance to 11 onychomycosis. 13,14 (Figure 2) The main differential
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Surg Cosmet Dermatol 2013;5(1):104.
12 Di Chiacchio N, Tavares GT, Padoveze EH, Bet DL, Di Chiacchio NG
nail plate. This technique allows the visualization of the gaps (per-
forations) of different shapes and sizes, suggestive of onychomatri-
coma. The technique is deemed straightforward, fast, cost effective,
and minimally invasive. In addition to allowing the diagnosis of the
tumor, it provides assistance in the differential diagnosis of onycho-
micosis using PAS staining, and enables the immunohistochemical
study of the nail plate. 21
Diagnosis is confirmed histologically. It is a fibroepithelial
tumor composed of two distinct areas: the proximal and distal zones.
The first is located below the posterior nail fold and is characterized
by deep epithelial invaginations filled by a thick keratin zone in the
shape of a "V", well-defined fibrillar and fibrotic stroma, in addition
to the thickening of the nail plate without cavities. The distal zone,
which corresponds to the lunula region, is characterized by finger-
like projections, perforations in the nail plate, and deep and poorly
delimited penetration of the connective stroma in the dermis. 4,7
The fingerlike projections are formed by matrix epithelium,
located around the connective tissue, in the antero-oblique axis, that
proliferate and cause perforations in the nail plate, generating cavi-
ties, which in the distal part of the lunula lose their epithelium and
are filled with serous fluid. 4,7
Some authors mention the presence of mast cells in the stro-
ma of onychomatricomas. 22 The keratinization zone can be adhe-
red to the nail plate. Thus, both the tumor and the removed plate
must be sent for histological examination. 4The splinter hemorrha-
ges seen in the nail plate’s proximal region, correspond to the fin-
gerlike projections’ loose vascular stroma. 12
The yellowish color occurs due to the thickening of the nail
plate, resulting from the layers of keratinization that involve the fin-
gerlike projections.. Its intensity is proportional to the degree of
thickening. 12
The main histological differential diagnoses are the fibrokera-
toma and the ungual fibroma. In the longitudinal cuts of the ony-
chomatricoma, the structure is reminiscent of a fibrokeratoma;
nevertheless that diagnosis may be excluded due to the presence of
multiple fingerlike projections, the absence of a cutaneous horn,
and the presence of cavities filled with serous fluid in the distal por-
tion of the nail plate. The onychomatricoma’s stroma, located in the
lunula, may suggest the diagnosis of fibroma, which in turn may be
discarded by the hyperplasic and onychogenic nature of the epithe-
lium. Moreover, ungual fibroma generates a longitudinal depression
in the nail plate, in the shape of a channel, due to the compression
in the nail matrix. 12
The immunohistochemical study using the cell proliferation
marker Ki67 (MIB-1) demonstrates a low rate of cell proliferation
in the onychomatricoma. 2The observed expression pattern of the
cytokeratin and integrins is identical to those of the normal matri-
cial epithelium, in spite of the fact that the antibody AE13—speci-
fic for the trichocystic keratin Ha 1-4 —can be potentially useful
as an onychomatricoma marker. 23
A study with adhesion proteins demonstrated the absence of
beta-catenin in comparison with other ungual tumors. 24 The invo-
lucrin is expressed from the basal layer up to the upper part of the
epithelium, where it is more pronounced and the transglutamina-
se-1 is limited. 5The immunophenotyping expresses CD34, but not
CD99 or epithelial membrane antigen, S100 protein, actin, and
desmin. 5
FIGURE 3: A)Bulging of the proximal fold (black arrow) and thickened nail
plate with yellowish color and distally striated hemorrhages; b) intraopera
tive aspect of the tumor with fibrous digitations (red arrow); c) posterior
view; d) ventral view of the nail plate with digitation impressions in the pro
ximal region, thickening and central yellowish color, and striated hemorr
hages close to the free border.
FIGURE 2: A)Nail plate thickened with yellowish color emulating onychomycosis. It is also possible to observe chromonychia suggestive of secondary
infection by pseudomonas; b) ultrasound showing tumor under the proximal nail fold, DUP longitudinal and transversal cuts: proximal nail fold; MP:
proximal matrix; PU: nail plate; LONG: longitudinal view; TRV: transversal view
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Surg Cosmet Dermatol 2013;5(1):104.
Onicomatricoma 13
In electron microscopy, the basal cells apparently contain a
reduced number of tonofilaments and desmosomes, which have a
non-uniform development. 8
TREATMENT
The treatment for onychomatricoma is surgical (Figure 4).
After anesthesia (proximal or distal locking) the proximal nail fold
is bent and the nail plate is gently removed in order to prevent the
villi from being torn. The tumor must be removed completely. Nail
dystrophy after surgical removal can occur depending on the pre-
servation of the nail matrix during the removal of the tumor. 25 ●
Figure 4: a) Bulging of the proximal
fold (black arrow), thickened nail
plate with yellowish color; b) thicke
ning of the nail plate with longitudinal
striae and visualization of cylindrical
tunnels in the distal section (red
arrow); c) Intraoperative aspect of
the tumor with fibrous digitations;
d) posterior view of the nail plate
with fibrous digitation impressions;
e) completely excised tumor;
f) results after seven months
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B
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1) About onychomatricoma it is correct to state, except for:
a) the avulsion of the nail plate is diagnostic
b) it is a benign tumor arising from the nail matrix
c) it is common in people of African origin and in children
d) it is usually painless and predominantly affects fingers
e) it can manifest with nodules in the proximal nail fold
2) The below are considered clinical signs of the onychomatri-
coma’s tetrad, except for:
a) yellowish longitudinal strip of varying thickness
b) splinter hemorrhages
c) longitudinal and transverse hypercurvature of the nail plate
d) blackened periungual pigmentation
e) fibrous digitations that emerge from the nail matrix
3) Select the correct choice regarding the clinical signs that
may arise in onychomatricoma:
a) nail dystrophy
b) melanonychia
c) nail bleeding
d) verrucous aspect in the nail fold
e) all of the above are correct
4) About the use of nail clipping for the diagnosis of onycho-
matricoma, we can say:
a) it is a fast, straightforward, cost effective and minimally invasive
examination
b) it is an old examination, which is not carried out anymore
c) it does not allow the visibility of the nail plate’s perforations due
to the tumor
d) it allows for ruling out other tumors of the nail matrix
e) it allows the histologic study of the nail plate, however it does not
allow the performing of an immunohistochemistry analysis
5) Among the onychomatricoma’s differential diagnoses is:
a) Bowen's disease
b) Subungual exostosis
c) Melanoma
d) Onychomycosis
e) all of the above are correct
6) Select the incorrect answer:
a) the visualization of fibrous digitations emerging from the nail
matrix and the cavities produced by them in the nail plate are fea-
tures of onychomatricoma.
b) ultrasonography is not an auxiliary method in the diagnosis of
onychomatricoma
c) it is the only tumor in which alterations in the nail plate are acti-
vely produced by the lesion
d) the main histological differential diagnoses are the fibrokeratoma
and the nail fibroma
e) the treatment for onychomatricoma is surgical
Questions for continuing medical education – CME
7) Regarding the examinations used in the diagnosis of ony-
chomatricoma, select the incorrect item:
a) ultrasonography can delineate the tumor
b) it is possible to see the splinter hemorrhages in the proximal por-
tion of the nail through dermoscopy
c) digital projections can be visualized in MRI
d) X-Ray is of utmost importance in the diagnosis of onychomatri-
coma
e) Nail clipping allows performing PAS
8) Which of the following findings is most suggestive of ony-
chomatricoma?
a) white longitudinal striations
b) longitudinal depression in the shape of channels
c) pyogenic granuloma in the nail edge
d) longitudinal perforations of the nail plate
e) Hutchinson sign
9) The onychomatricoma’s histology evidences:
a) basaloid cells with myxoid stroma in the dermis
b) matrix proliferative epithelium that invades the nail plate
c) hyperkeratosis with parakeratosis and presence of koilocytes
d) atypical keratinocytes in the nail bed
e) atypical melanocytes with increased mitotic activity and dermal
invasion
10)Select the right option regarding the treatment of onycho-
matricoma:
a) surgery is the treatment of choice
b) the proximal matrix must be removed in order to prevent recur-
rence
c) nail dystrophy occurs invariably in the postoperative
d) the complete removal of the nail apparatus is performed during
the surgery
e) the treatment may be clinical
Answers must be submitted online using the website
www.surgicalcosmetic.org.br.
The deadline for submitting answers will be provided by e-mail
with a direct link for accessing the journal.
Key:
Hormone in the rejuvenation: a review of its real
effectiveness. Cosmet Dermatol Surg 2012; 4(4):322-30.
1d 2b 3c 4d 5b 6a 7c 8a 9d 10c
Surg Cosmet Dermatol 2013;5(1):104.
14 Di Chiacchio N, Tavares GT, Padoveze EH, Bet DL, Di Chiacchio NG