Clear Cell Myoepithelial Carcinoma of the Upper Lip -A Rare Case Report
Swati GOTMARE1, Anish GUPTA2, Megha JAIN2, Mandavi WAGHMARE3
1Department of Oral Pathology, DY Patil University School of Dentistry, MUMBAI, INDIA
2People's Dental Academy, BHOPAL, INDIA
3Department of Oral Medicine & Radiology, DY Patil University School of Dentistry, MUMBAI, INDIA
Keywords: Myoepithelial carcinoma, Clear cell carcinoma, Upper lip
Myoepithelial carcinomas are quite infrequent neoplasms and coupled with their diverse morphological appearance are interesting as far as
diagnosis and management is concerned. They account for less than 1% of all salivary gland tumors. The variable morphologic appearance of
myoepithelial carcinoma leads to a wide differential diagnosis, including primary salivary gland tumors and metastatic tumors. The prognosis of
these tumors is not fair as they are locally aggressive and approximately one third of the patients die of the pathology. We report a case of clear cell
variant of myoepithelial carcinoma in an unusual location, i.e. the upper lip. The treatment carried out was wide surgical resection. The patient
was followed up for 2 years and was symptom free. The clear cell variant of myoepithelial carcinoma is extremely rare and only about 51 cases of
this variant affecting the salivary glands have been reported worldwide so far.
Salivary gland neoplasms pose great challenges in
management because of their varied morphology and
unpredictable behavior. Myoepithelial Carcinomas (MC)
account for 0.4 to 0.6 % of all salivary gland neoplasms1
This neoplasm was introduced by Stromeyer et al. in 1975.
Parotid glands are affected most commonly, followed by
the submandibular and minor salivary glands. The most
common site for intra-oral presentation is the palate2
There is usually a precursor lesion such as pleomorphic
adenoma, myoepithelioma associated with it but it may
also arise de novo3
. MC is difficult to diagnose clinically
and histopathologically and may mimic a benign neoplasm.
Immunohistochemical (IHC) markers such as CAM5.2,
AE1:AE3, 34βE12, cytokeratin 7, cytokeratin 14, vimentin,
S-100 protein, smooth muscle actin, CD 10, calponin,
muscle-specific actin, glial fibrillary acidic protein,
carcinoembryonic antigen, and epithelial membrane
antigen have been used to confirm the diagnosis4,5
report a rare case of Clear Cell Myoepithelial Carcinoma
(CCMC) of the upper lip. To the best of our knowledge,
this is the first case to be reported in the upper lip and
histopathologically presented as a clear cell variant. A panel
of IHC markers was applied to confirm the diagnosis.
A 46-year-old female patient reported to us with a
complaint of mild extra-oral and intra-oral swelling for the last 6 months. Extra-orally the swelling was extending
superior-inferiorly from the base of the nose to the philtrum
and medio-laterally from the midline to the centre of
the upper lip on the left side with an approximate size of
3 x 2 cm. Intra-orally, a diffuse swelling obliterating the
labial vestibule extending from the maxillary right central
incisor and crossing the midline up to the left canine
region was seen. The swelling was soft to firm on palpation
with a smooth glistening surface appearing similar to the
surrounding mucosa (Figure 1
). Occlusal radiograph
showed involvement of the medial and lateral alveolar
process of maxillary left central incisor with horizontal
bone loss and saucerization. CT scan revealed an expansile
lesion involving the maxillary anterior region causing
expansion of the buccal cortical plate (Figure 2
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|Figure 1: Intra-oral presentation reveals obliteration of labial
The patient’s personal and family history were noncontributory.
Metastasis from primary tumor of other sites
was ruled out. There was no evidence of any metastasis.
Blood investigations were within normal limits. A
provisional diagnosis of salivary gland tumor was made
and accordingly an incisional biopsy was performed which
revealed malignancy of salivary gland. The tumor was
surgically removed and submitted for histopathological
examination. Gross specimen measured around 3x2
cm, was non-encapsulated, multinodular and presented
irregular borders. It was firm in consistency and grayish
white in color. Microscopy showed tumor nodules
composed of epitheloid cells arranged in diffuse sheets, nests and cords separated by fibrous septa. Tumor cells
had round to oval nuclei, vesicular chromatin, prominent
nucleoli and a moderate amount of eosinophilic cytoplasm.
Mitotic figures ranged from 5 to 7 per 10 high power field.
Many of the cells showed partially clear cytoplasm (Figure
3). The stroma contained hyalinised material. No areas
of necrosis were evident. There was presence of invasion
in the adjacent alveolar bone. A panel of IHC markers
consisting of alpha-SMA (Figure 4), HMW cytokeratin
(Figure 5), calponin (Figure 6), CD-10 (Figure 7) and
EMA were applied. They were all indicated by dark brown
cytoplasmic staining. The results were positive for all the
markers, except EMA. The diagnosis was confirmed as
CCMC. The patient was followed up for 2 years and there
was no complaint or recurrence.
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|Figure 3: Neoplasm showing mixture of epitheloid and clear cells
(devoid of cytoplasm) in a hyalinised stroma and cytological
pleomorphism (H&E; 100).
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|Figure 5: Tumor cells are positive for high molecular weight
cytokeratin (HMWCK; x400).
Myoepithelial cells were first introduced by Krause in 1865
in breast tissue followed by its observation in salivary gland
. The physiologic roles of these cells are contraction,
propagation of neural stimuli, basement membrane
production, transport of metabolites and tumour
. MC or malignant myoepithelioma
is defined as a malignant epithelial neoplasm in which
the predominant differentiation of the tumor cells is
. There is equal sex distribution in the
various reported cases. It is believed that a precursor lesion
such as pleomorphic adenoma may be present or MC may
arise de novo. Some authors believe that de novo MCs are
more aggressive and may have a poor prognosis9
final outcome of MC is controversial in either type of case5
. Major salivary glands are more commonly affected
than the minor ones although a few studies have reported
. The CCMC has been reported
in the parotid gland, submandibular gland and intra-orally
in the palate, retromolar area, maxillary sinus and even
the base of the tongue. To the best of our knowledge, this
variant in the unusual location of the upper lip is the first to
be reported. The presentation of neoplastic myoepithelial
cells in MC is the major cause of a diagnostic dilemma
as they occur in epitheloid (most predominant), spindle,
plasmacytoid and clear forms8
. The tumor, along with
the cells, also shows myxoid or hyaline-like material in the
. In our case, there was mixture of epitheloid
and clear cells (percentage of clear cells being more than
50%) and the matrix showed hyaline material. MCs may
resemble a benign tumor and the features demarcating
MCs from benign tumors are cytological pleomorphism,
mitosis, necrosis and invasion of adjacent tissues.
Khademi B et al. have shown that preoperative diagnosis of malignant myoepitheliomas is unreliable11
nuclei show cytological atypical changes in the form of
pleomorphism, mitotic activity, and vesicular chromatin.
MC of spindle cell type is rare, having a clinical presentation
as an ulcerative lesion, and has a poor prognosis12
The clear cells of CCMC display typical signet ring or
lipoblast shapes, although there may be admixture of
other cells such as epitheloid, spindle or plasmacytoid13,14
. It has been reported that MC may show presence
of osteoclast-like giant cells and the prognosis is adversely
affected when they are present5
. Myoepithelial cells
are capable of producing basement membrane and nonbasement
membrane proteins (chiefly chondroitin sulfate
proteoglycans), which leads to formation of a myxoid
. IHC markers such as S-100, alpha-SMA,
cytokeratins, calponin, EMA, and vimentin have been used
to confirm the myoepithelial cells2,16
. The cells show
intense staining for these markers, although at times the
staining may be sparse or negative. This may be attributed to the fact that the myoepithelial cells may show different
stages of differentiation. It has been suggested that p53 can
be a useful predictor for prognosis. Its over-expression is
directly related to compromised survival rates. CCMCs
may harbor the Ewing sarcoma breakpoint region 1
(EWSR1) rearrangement and therefore may be genetically
related to EWSR1-rearranged cutaneous myoepithelial
. The features of our case were consistent with
the criteria of CCMC. Due to scanty literature on CCMC
and moreover the rare location of the upper lip, further
longitudinal studies may be required. The treatment for
this tumor is wide surgical resection and a close follow-up.
The prognosis of CCMC is not very favourable.
In conclusion, MCs are extremely noteworthy tumors that
mostly affect major salivary glands. Very few cases have
been documented in the oral cavity. The tumor cells may
presented as epitheloid, spindle or plasmacytoid types.
The clear cell variant is extremely rare and we report this
variant in a very unusual location, the upper lip, invading
the alveolar bone. The prognosis of this tumor is guarded.
The only treatment is surgical resection with wide margins.
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