Lung
Salivary gland type tumors
Mucoepidermoid carcinoma


Topic Completed: 1 May 2018

Minor changes: 3 September 2020

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PubMed Search: Mucoepidermoid carcinoma [title] lung tumor AND (free full text[sb])

Roseann Wu, M.D., M.P.H.
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Cite this page: Wu R. Mucoepidermoid carcinoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lungtumormucoepidermoid.html. Accessed October 20th, 2020.
Definition / general
  • Low grade or high grade salivary gland type tumor with mucous secreting cells, squamous cells and intermediate cells
  • Distinguished from other lung cancers by central or peribronchial location, mucous cells, lack of keratinization, expression of p63 and MAML2 rearrangement (Mod Pathol 2014;27:1479)
Essential features
  • Most common salivary gland type tumor in the lung, tends to arise centrally
  • Similar morphology to mucoepidermoid carcinoma arising in the head and neck with a mixture of mucous cells, squamous cells and intermediate cells; must exclude metastasis
  • Strong association with t(11;19)(q21;p13) and MAML2 rearrangement by fluorescence in situ hybridization (FISH)
  • Squamous component stains with p63 and p40
Terminology
  • Same diagnostic terminology as used in the salivary gland
ICD coding
  • C33 Malignant neoplasm of trachea
  • C34.00 Malignant neoplasm of unspecified main bronchus
  • C34.01 Malignant neoplasm of right main bronchus
  • C34.02 Malignant neoplasm of left main bronchus
  • Code more peripheral lesions depending on specific lobe, laterality and extent
Epidemiology
Sites
  • Any lung lobe, usually in relation to large bronchi
Pathophysiology
Etiology
  • May arise from submucosal bronchial glands
Clinical features
  • Large central tumors cause obstructive symptoms such as dyspnea, cough, hemoptysis or pneumonia
  • Peripheral lesions may be asymptomatic
Diagnosis
  • Bronchoscopy may be used to directly visualize and sample an endobronchial tumor
  • Diagnosis may be difficult in small biopsies; may mimic primary non small cell lung carcinoma
Radiology description
  • Can be difficult to detect on imaging due to small size of tumor, endobronchial location, association with pneumonia or atelectasis (Arch Pathol Lab Med 2007;131:1400)
  • On CT, markedly enhanced homogeneous central bronchial nodule / mass suggests low grade mucoepidermoid carcinoma (MEC); high grade MEC tends to be peripheral with poorly defined margins, lobular, heterogeneous with less enhancement (AJR Am J Roentgenol 2015;205:1160)
  • Uncommon findings included cavitation, diffuse thickening or spiculation (Clin Imaging 2012;36:8)
Radiology images

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Heterogeneously enhancing lesion

Heterogeneously enhancing lesion

Mass shadow measuring 30 mm

Mass shadow measuring 30 mm

Mass in right upper lobe and left hilum

Mass in right upper lobe and left hilum

Prognostic factors
Case reports
Treatment
Clinical images

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Well circumscribed endobronchial tumor

Well circumscribed endobronchial tumor

Gross description
  • Polypoid, exophytic growth or sessile tumor in major bronchi, may be > 5 cm
  • Generally well circumscribed and smooth with tan to yellow cut surface
  • May be solid or cystic and potentially show glistening mucoid material
Gross images

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Mucoepidermoid carcinoma of airways

Mucoepidermoid carcinoma of airways

Tumor in middle lobe bronchus

Tumor in middle lobe bronchus

Microscopic (histologic) description
  • Low grade has more cysts and mucous cells; high grade has more solid or nested growth, atypia, mitotic activity, necrosis, hemorrhage
  • Mucus secreting cells, squamoid cells without significant keratinization, intermediate type cells
  • Mucus secreting cells usually large with light blue-gray mucinous cytoplasm; variants include columnar, goblet, cuboidal, clear or oncocytic cells (Arch Pathol Lab Med 2007;131:1400)
  • Squamous cells show intercellular bridges but no keratin whorls or pearls; intermediate cells usually polygonal with bland nucleus (Arch Pathol Lab Med 2007;131:1400)
  • May show areas of papillary growth or spindled cells
  • May have dense lymphoplasmacytic infiltrate (Am J Surg Pathol 2005;29:407)
  • Lack in situ carcinoma of overlying epithelium
Microscopic (histologic) images

Contributed by Roseann Wu, M.D., M.P.H. and Yale Rosen, M.D.
Low grade mucoepidermoid carcinoma

Low grade mucoepidermoid carcinoma

Low grade MEC mucicarmine stain

Low grade MEC mucicarmine stain

High grade mucoepidermoid carcinoma High grade mucoepidermoid carcinoma

High grade mucoepidermoid carcinoma

Mucoepidermoid carcinoma, low grade Mucoepidermoid carcinoma, low grade

Mucoepidermoid carcinoma, low grade


Stroma infiltrated by inflammatory cells

Stroma infiltrated by inflammatory cells



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MEC of lung

MEC of lung

EGFR seen in squamous and intermediate cells

EGFR seen in squamous and intermediate cells

Pulmonary MEC Pulmonary MEC Pulmonary MEC

Pulmonary MEC

MEC-like pulmonary carcinoma

MEC-like pulmonary carcinoma

Virtual slides

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Mucoepidermoid carcinoma of the lung, from Juan Rosai’s Collection of Surgical Pathology Seminars Mucoepidermoid carcinoma of the lung, from Juan Rosai’s Collection of Surgical Pathology Seminars Mucoepidermoid carcinoma of the lung, from Juan Rosai’s Collection of Surgical Pathology Seminars Mucoepidermoid carcinoma of the lung, from Juan Rosai’s Collection of Surgical Pathology Seminars

Mucoepidermoid carcinoma of the lung, from Juan Rosai’s Collection of Surgical Pathology Seminars

Cytology description
  • Mixture of squamoid cells, mucous cells and intermediate cells
  • Diff-Quik with numerous tight clusters of relatively small and bland cells with well defined but scant cytoplasm, central round and uniform nuclei with small nucleoli; second population of glandular appearing cells with cytoplasmic vacuoles with mucin, focal extracellular metachromatic mucinous material (Diagn Cytopathol 2013;41:1096)
Positive stains
Negative stains
Molecular / cytogenetics description
  • MAML2 rearrangement most common molecular genetic event, found more in low grade tumors (PLoS One 2015;10:e0143169)
  • May stain with epidermal growth factor receptor (EGFR) but does not show the mutation or alterations in copy number (Mod Pathol 2008;21:1168)
  • Reciprocal translocations, including t(1;11)(p22;q13) with overexpression of cyclin D1, t(11;19)(q14-21;p12) and t(11;19)(q21;p13) which encodes MECT1-MAML2 (MECT1 also known as CRTC1) (Arch Pathol Lab Med 2007;131:1400)
Molecular / cytogenetics images

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<i>MAML2</i> rearrangement by FISH

MAML2 rearrangement by FISH

Differential diagnosis
Additional references
Board review style question #1
    Rearrangement of which gene would support the diagnosis of mucoepidermoid carcinoma of the lung?

  1. APC
  2. BRAF
  3. MAML2
  4. PIK3CA
  5. PLAG1
Board review answer #1
C. MAML2
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