“A 13 y/o Boy with a Posterior Maxillary
Nodule”
California Tumor Tissue Registry’s
Case of the Month
CTTR COTM Vol. 17:4
January, 2015
www.cttr.org
A 13year-old boy presented with a left posterior maxillary nodule which had developed
over a two year period.
The excised 2 x 2 x 1.5 cm oval, lobular nodule had a dark-red to pink-gray cut surface.
Microscopically, it consisted of polygonal cells with eccentric nuclei and clear or mucincontaining cytoplasm that were admixed with nests of cells with eosinophilic cytoplasm,
intercellular bridges and basal cells (Figs. 1 and 2). Pools of extracellular mucin were
also seen. The cells failed to show mitotic figures and had only minimal nuclear atypia
(Fig. 3). The nodule involved maxillary bone (Fig. 4).
Diagnosis: Central/intraosseous Mucoepidermoid Carcinoma of Maxilla
Tae Hun Kim, MSIV and Donald R. Chase, M.D.
Department of Pathology and Human Anatomy,
Loma Linda University Medical Center, Loma Linda, California
California Tumor Tissue Registry, Loma Linda, California
Mucoepidermoid carcinoma (MEC) is the most common malignant salivary gland tumor.
It occurs in both minor and major salivary glands with a predominance in the latter,
especially the parotid gland. MEC can rarely occur in sites that are normally devoid of
salivary gland tissue, e.g. the mandible and maxilla. The term central or intraosseous
MEC is utilized for these cases.
Central MEC is a rare tumor with an estimated incidence rate of 2-4% of all MEC. Like
traditional MEC, central MEC affects females more than men. It is more common in the
molar regions of the mandible than the maxilla. The clinical presentation varies from
asymptomatic individuals with an incidental nodule on radiologic evaluation to
symptomatic individuals with swelling, pain, facial asymmetry, or trismus. Radiology
usually demonstrates a well-circumscribed unilocular/multilocular radiolucent nodule
with evidence of bony destruction.
The exact origin of central MEC is unknown. Some authors proposed that it originates
from ectopic salivary gland tissue, while others thought that it develops from existing
odontogenic cysts. The latter theory is favored because metaplastic cells have been seen
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in odontogenic lesions. Half of central MEC are associated with cyst(s) or unerupted
tooth, and other neoplasms have been shown the develop from odontogenic cysts.
Histologically, central MEC is similar to that of low-grade MEC. It consists of mucous,
epidermoid, and basal cells invading in nests and solid sheets. Pleomorphism is absent or
minimal.
Immunohistochemically, central MEC are positive for keratin (CK7 and CK14) and
mucin markers (MUC1, MUC2, MUC4, MUC5AC, and MUC5B). Central MEC can
also demonstrate the MAML2 gene rearrangement.
Accepted criteria for the diagnosis of central MEC includes:
 Presence of intact cortical plates
 Radiologic evidence of bony destruction
 Exclusion of another primary tumor
 Histopathological confirmation
 Detectable intracellular mucin
Brookstone and Huvos proposed a staging system for central MEC:
 Stage I – Intact cortical bone without clinical bony expansion
 Stage II – Intact cortical bone with clinical bony expansion
 Stage III – Cortical bone perforation, breakdown of overlying periosteum, or
nodal spread
The differential diagnosis includes:
 Glandular odontogenic cysts – Locally aggressive developmental cyst that occurs
mostly in the mandible with an anterior predilection; cyst lined by stratified
squamous epithelium, cuboidal, or columnar ciliated cells. Small microcysts and
clusters of mucous cells can also be present. Because of its histologic similarity
with central MEC, invasive growth, negative immunohistochemical staining of
Maspin (expressed in MEC), and genetic abnormality are helpful in distinguishing
these entities.
 Keratocystic odontogenic tumor – Parakeratinized stratified squamous epithelium
with uniform thickness. No mucous cells are present.
 Adenosquamous carcinoma – Central MEC does not have anaplastic nuclear
features or squamous cell carcinoma in-situ.
 Metastatic lesions to mandible/maxilla – Presence of primary tumor elsewhere in
body
Central MEC may be treated by either conservative or aggressive surgical resection.
Recurrence rates are up to 40% and 13% for conservative and aggressive resections,
respectively. Less than 10% of central MEC cases present with metastatic disease.
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Suggested Reading:
Brookstone MS, Huvos AG. Central salivary gland tumors of the maxilla and mandible: a
clinicopathologic study of 11 cases with an analysis of the literature. J Oral Maxillofac Surg.
1992; 50:229-36.
Moghadam SA, Moghadam FA. Intraosseous mucoepidermoid carcinoma: Report of Two Cases.
J Dent. 2014; 15(2): 86-90.
Rosai J. Rosai and Ackerman’s Surgical Pathology, 10th ed. Edinburgh, Mosby, 2011; 831-832.
Spoorthi BR, Rao RS, Rajashekaraiah PB, Patil S, Venktesaiah SS, Purushothama P.
Predominantly cystic central mucoepidermoid carcinoma developing from a previously diagnosed
dentigerous cyst: case report and review of the literature. Clin Pract. 2013 Jun 20;3(2)e19.
Wenig B. Atlas of Head and Neck Pathology, 2nd ed: Philadelphia, Saunders/Elsevier, 2008; 615622.
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