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How to cite this article: Bartoš V, Kullová M. Pilomatrical carcinoma - a case report and review of the literature. Our Dermatol Online. 2018;9(2):170-173.
Submission: 12.10.2017; Acceptance: 08.02.2018
Pilomatrical carcinoma - a case report and review of
Pilomatrical carcinoma - a case report and review of
Vladimír Bartoš1, Milada Kullová2
1Department of Pathology, Faculty Hospital in Žilina, Slovakia, 2Department of Dermatovenerology, Faculty Hospital in
Corresponding author: Dr. Vladimír Bartoš, E-mail: email@example.com
Pilomatrical carcinoma (PC) is a very rare low-grade
cutaneous malignancy with matrical differentiation,
considered to be the malignant counterpart of
pilomatrixoma. It was first described in 1980 by
Lopansri and Mihm  and until now, about 140 cases
have been published in the English literature .
Given the rarity of this neoplasm, there is impossible
to estimate its incidence, and knowledge on etiology,
pathogenesis and biological behaviour is only sparse.
Here, we report an additional case of PC with
uncommon histological feature and provide an up to
date review of the literature.
An 85-year-old man with a history of multiple cutaneous
basal cell carcinomas presented with a polypoid skin
tumor in the left lumbal region. He visited a dermatology
outpatients‘ department. On physical examination, the
lesion was sharply demarcated, dark-brow in color and
measured 12x8x6 mm. A presumptive clinical diagnosis
of BCC was made. The patient was reffered to the
hospital, when a total surgical excision of tumor had
Histopathology and Immunohistochemistry
Biopsy specimen was completely processed
using standard hematoxylin and eosin stained
paraffin sections along with a wide spectrum of
immunohistochemical markers, summarized in
Table 1. Histology revealed solid tumor formations,
which were predominantly composed of pleomorphic
basaloid cell population with frequent mitoses. This
cellular component was admixed with multiple
aggregates of anuclear cells with eosinophilic cytoplasm
reminiscent of „shadow” cells seen in pilomatrixoma,
as well as with whorls of pink keratin material
reminiscent of squamoid pearls (Figs. 1 and 2). There
was very high mitotic and proliferative activity. The
We report a case of an 85-year-old man, who presented with a polypoid skin tumor in the left lumbal region. Histology
revealed a malignant tumor composed predominantly of pleomorphic basaloid cell population with a high mitotic
and proliferative activity. This cellular component was admixed with aggregates of anuclear cells with eosinophilic
cytoplasm reminiscent of „shadow” cells seen in pilomatrixoma, as well as with whorls of keratin material reminiscent
of squamoid pearls. Immunohistochemically, the basaloid tumor part was positive for CD10, p120catenin and CD138
and very sporadically positive for cytokeratin 19 and BerEP4. Cytokeratin 20 was negative and epithelial membrane
antigen labelled only eosinophilic squamoid structures. In some areas, numerous interspersed dentritic melanocytes
strongly immunoreactive for S-100 protein were arranged singly and in larger expansile nests within basaloid tumor
mass. Histopathology and immunoprofile of lesion favored a diagnosis of pilomatrical carcinoma with intratumorous
melanocytic proliferation. To the best of our knowledge, only a few such cases have been described untill now.
Key words: Pilomatrical carcinoma; Pilomatrixoma; Adnexal tumors
© Our Dermatol Online 2.2018 171
Ki-67 index reached 90% (Fig. 3) and more than 40
mitotic figures per 10 high power fields were counted.
Immunohistochemically, the basaloid tumor part
was apparently positive for CD10, p120catenin and
CD138 and very sporadically positive for cytokeratin
19 and BerEP4 (both < 5% of cells). Cytokeratin
20 was negative and epithelial membrane antigen
(Fig. 4) labelled only eosinophilic squamoid structures
and „shadow” cells. Interestingly, in certain areas,
numerous interspersed dentritic melanocytes strongly
immunoreactive for S-100 protein were arranged
singly and in larger expansile nests within basaloid
tumor mass (Fig. 5). The tumor extended into the
epidermis, resulting in focal ulceration. At the base, it
grew invasively with infiltration of the dermis. Neither
lymphovascular nor perineural tumor invasion was
found. A spectrum of histomorphological findings
along with immunophenotype favored a diagnosis
of pilomatrical carcinoma with intratumorous
melanocytic proliferation. Resection margins were
free of tumor and a minimum of 5-mm clearance was
achieved. The patient continued to be under close
follow-up and at the time this report was written
(16 months after operation), no evidence of local
recurrence or distant metastasis have been found.
PC is exceedingly rare cutaneous malignancy derived
from the hair follicle matrix. It shows a predilection
for middle aged and elderly individuals [3,4], but
the cases involving the young people have also been
described [5-7]. PC has no specific anatomic location
and may arise anywhere in the body. Although it has
been shown a slight predilection for the head and neck
region [3,4,8-12], various other sites affected have been
reported to date, such as the back [3,13], chest [3,4],
upper limbs [3,7,14], lower limbs [2,15], buttock 
or vulva .
Table 1: Details of the primary antibodies and the corresponding
detection systems used in the present case
Antigen Antibody Source Dilution
monoclonal, clone MM1
monoclonal, clone 56C6
monoclonal, clone MRQ-5
monoclonal, clone MI15
monoclonal, clone RCK108
monoclonal, clone Ks20.8
monoclonal, clone BerEP4
monoclonal, clone E29
monoclonal, clone 15E2E2
1 : 200
ready to use
1 : 25
ready to use
ready to use
1 : 50
ready to use
1 : 100
1 : 100
Figure 1: Predominant pleomorphic basaloid tumor cell population
admixed with aggregates of eosinophilic anuclear cells and whorls of
pink keratin material. (H&E, original magniﬁ cation 40x).
Figure 2: Detail on interface between basaloid tumor part and anuclear
eosinophilic cells reminiscent of „shadow” cells, as well as whorls of
keratin squamoid structures. (H&E, original magniﬁ cation 200x).
Figure 3: High proliferative activity (Ki-67 index) of basaloid cell
population. (original magniﬁ cation 200x).
© Our Dermatol Online 2.2018 172
The origin of PC still controversial. Based on the
literature research, the vast majority of the cases
have been shown without histologic association with
its benign counterpart, the finding supporting the
development ab initio. Nevertheless, the literature
notes some case reports of patients in whom a biopsy
specimen first identified the tumor as a benign lesion
that underwent carcinomatous changes after a certain
period of latency [6,10,15]. In the present case, we did
not observe any benign tumor component within the
tumor mass, so it was probably malignant from the onset.
In this regard, it should be mentioned that although
PC is a malignant counterpart of pilomatrixoma,
and both tumors share common histopathologic and
immunophenotypic features, their epidemiology is
different. While benign pilomatrixomas are seen more
often in women (female/male ratio 3:1), PCs are seen
in the opposite ratio (female/male ratio 1:3-5) [3,4,14].
Further, pilomatrixomas typically occur in children and
young adults, but PCs usually occur in older people in
the 5th and 6th decades of life [4,14].
A definite diagnosis of PC and in particular, its
differentiating from pilomatrixoma remains based
only on the histomorphological features. However,
much of the histopathology of PC resembles its
benign counterpart and the criteria of malignancy
have not been well established. In general, these
include tumor asymmetry, poor circumscription,
marked anaplasia of basaloid neoplastic cells with
vesicular nuclei and prominent nucleoli, frequent
atypical mitoses, areas of necrosis, infiltrative growth
pattern, sometimes ulceration and vascular and/or
perineural invasion [4,12,15]. In our case, the vast
majority of them have been clearly visible confirming
a malignancy. PC possess no specific immunoprofile
and immunohistochemistry studies have not yielded
markers that may consistently and definitively confirm
a diagnosis. Moreover, many case reports published
until now have not performed special immunoanalyses.
In general, benign and malignant cutaneous adnexal
tumors of follicular origin variably express the „hair
differentiation“ keratins, such as cytokeratin 7, 8,
18 and 19 . In both, pilomatrixoma and PC,
the basaloid cells showed a nuclear and cytoplasmic
expression of β-catenin  and in pilomatrixoma, they
showed strong positivity for CD138 and CD10 .
Two papers [7,12] also demonstrated a reactivity for
BerEP4 in PC.
An interesting feature in our case was a remarkable
population of dentritic melanocytes within a basaloid
tumor tissue. In the last years, there were reported the
cases of PCs accompanied by marked intratumorous
melanocytes colonisation [2,11,13,19]. The terminology
of this entity is inconsistent, since it has been entitled
as melanocytic pilomatrix carcinoma , pilomatrix
carcinoma with intralesional melanocytes ,
matrical carcinoma with melanocytic proliferation ,
or matrical carcinoma with prominent melanocytic
hyperplasia . Nevertheless, they are likely the same
tumor entity under the different names. We believe
that our current lesion represents an additional case
of this unique variant. This histologic feature probably
recapitulates the intimate relationship existing between
matrical epithelium and melanocytes in the embryonal
hair follicle or in the anagen stage of the hair cycle.
Theoretically, a presence of numerous melanocytes
in PC should not be surprising, but is in fact a very
unusual feature. In the series of 20 PCs published by
Figure 4: Positivity for EMA in eosinophilic tumor component, while
basaloid tumor population is negative. (original magniﬁ cation 100x).
Figure 5: Strong positivity for S-100 protein in dentritic melanocytes
interspersed within basaloid tumor mass. (original magniﬁ cation 100x).
© Our Dermatol Online 2.2018 173
Sau et al. , immunohistochemical stain for S-100
protein was negative in all tumors.
From the clinical point of view, PC usually behaves like
a low-grade malignancy, but it possess a high propensity
for local recurrence. In the study of Sau et al. ,
approximately half of the cases investigated relapsed.
A few PCs with regional and/or visceral metastases have
been published until now [3,8,9], some of which have
led to death within a relatively short period from time
of diagnosis [8,9]. Although PC metastasizes in only
about 10% of the cases, when it becomes metastatic, a
mortality rate approaches nearly 100% . Therefore,
a close clinical follow-up after diagnosis is a priority for
further managment of the patient.
In conclusion, we described a unique case of
PC accompanied by intratumorous melanocytic
proliferation. To the best of our knowledge, only a
few such cases have been published untill now. The
biologic significance of melanocytic proliferation in
this rare cutaneous neoplasm is uncertain and requires
further study. It would be interesting to analyze larger
number of the cases to elucidate, whether they may
be considered a distinct histologic variant of PC with
possibly different biological behaviour.
The examination of the patient was conducted
according to the Declaration of Helsinki principles.
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Copyright by Vladimír Bartoš, et al. This is an open-access article
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Source of Support: Nil, Conﬂ ict of Interest: None declared.