Mucinous (“Colloid”) Carcinoma

Key Facts

Terminology

Mucinous cystadenoma, mucinous cystic tumor, multilocular cystic carcinoma, mucinous cystic tumor of borderline malignancy

Macroscopic Features

Well-defined tumor mass with mucoid consistency, solid &/or cystic
Varies from 1 to > 10 cm

Microscopic Pathology

Extensive areas of mucinous deposition
Alveolar wall lined with mucinous epithelium
Single cells or clusters of cells embedded in mucin

Ancillary Tests

TTF-1 nuclear positivity (may be negative in some cases)
CK7 cytoplasmic positivity
CK20 negative (may be positive in some cases)
CDX2 negative (may be positive in some cases)

Top Differential Diagnoses

Metastatic mucinous carcinoma of extrathoracic origin
- Clinical history of or clinical evaluation for colonic, ovarian, breast, or urachal carcinoma will be important
- Immunohistochemical studies important in determining primary site

Diagnostic Checklist

Extensive mucin
Alveolar wall lined with mucinous epithelium

Gross photograph of mucinous carcinoma shows a well-defined subpleural tumor with a mucoid consistency. No evidence of necrosis or hemorrhage is present.

Lung parenchyma is replaced by extensive areas of mucoid material that destroy alveolar walls. This presentation may mimic a benign mucinous cyst.

TERMINOLOGY

Synonyms

Mucinous cystadenoma, mucinous cystic tumor, multilocular cystic carcinoma, mucinous cystic tumor of borderline malignancy

Definitions

Epithelial neoplasm with extensive mucin production

CLINICAL ISSUES

Epidemiology

Incidence
- Pure colloid carcinomas of the lung are rare
Age
- Colloid carcinomas are more common in adult patients
Gender
- No gender predilection

Presentation

Cough
Chest pain
Shortness of breath
Asymptomatic

Treatment

Surgical approaches
- Lobectomy

Prognosis

Depends on staging at time of diagnosis

MACROSCOPIC FEATURES

General Features

Well-defined tumor mass
Mucoid consistency
Cystic changes may be present

Size

Varies from 1 to > 10 cm

MICROSCOPIC PATHOLOGY

Histologic Features

Extensive areas of mucin deposition
Alveolar wall lined with mucinous epithelium
Single cells or clusters of cells are seen floating in the mucin

Predominant Pattern/Injury Type

Mucinous

Predominant Cell/Compartment Type

Epithelial

DIFFERENTIAL DIAGNOSIS

Metastatic Mucinous Carcinoma of Extrathoracic Origin

Clinical history of or clinical evaluation for colonic, ovarian, breast, or urachal carcinoma will be important
Immunohistochemical studies important in determining primary site

Bronchioloalveolar Carcinoma (BAC), Mucinous Variant

In BAC, lepidic growth pattern is characteristic feature in which alveolar lining is substituted by mucinous type of epithelium
BAC commonly will diffusely involve the entire lung or extensive areas of it
Immunohistochemical features of BAC and colloid carcinoma may be similar

DIAGNOSTIC CHECKLIST

Clinically Relevant Pathologic Features

Gross appearance

Pathologic Interpretation Pearls

Extensive mucin
Alveolar wall lined with mucinous epithelium

GRADING

Colloid Carcinoma

Considered low-grade malignant neoplasm
Behavior determined by pathological staging at time of diagnosis

SELECTED REFERENCES

1. Bacha D et al: A pulmonary mucinous cystic tumour of borderline malignancy. Pathologica. 100(3):189-91, 2008

2. Maeda R et al: Primary pulmonary mucinous (colloid) adenocarcinoma. Gen Thorac Cardiovasc Surg. 56(4):195-8, 2008

3. Moran CA: Pulmonary adenocarcinoma: the expanding spectrum of histologic variants. Arch Pathol Lab Med. 130(7):958-62, 2006

4. Türüt H et al: Primary pulmonary mucinous adenocarcinoma in a 15-year-old boy. Eur J Cardiothorac Surg. 29(5):851-3, 2006

5. Brownlee NA et al: Mucinous (colloid) adenocarcinoma of the lung. Arch Pathol Lab Med. 129(1):121-2, 2005

6. Okimasa S et al: Mucinous (colloid) adenocarcinoma. Jpn J Thorac Cardiovasc Surg. 53(6):305-8, 2005

7. Jayaram G et al: Mucinous carcinoma (colloid carcinoma) of the lung diagnosed by fine needle aspiration cytology: a case report. Malays J Pathol. 25(1):63-8, 2003

8. Moran CA. Mucin-rich tumors of the lung. Adv Anat Pathol. 2(5):299-305, 1995

9. Moran CA et al: Mucinous (so-called colloid) carcinomas of lung. Mod Pathol. 5(6):634-8, 1992

10. Graeme-Cook F et al: Pulmonary mucinous cystic tumors of borderline malignancy. Hum Pathol. 22(2):185-90, 1991

Tables

Immunohistochemistry

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