It is a common type of lung cancer and its incidence is increasing, particularly in women. Adenocarcinoma is the one cell type of primary lung tumor that occurs more often in non-smokers and in smokers who have quit. Most adenocarcinomas arise in the periphery of the lung.
Bronchioloalveolar carcinoma is considered as a variant of adenocarcinoma.
Histologic subtypes:
acinar
papillary
bronchioloalveolar carcinoma
non-mucinous
mucinous
mixed mucinous and non-mucinous or indeterminate cell type
solid adenocarcinoma with mucin
adenocarcinoma with mixed subtypes
Rare variants:
well-differentiated fetal adenocarcinoma
mucinous ('colloid') adenocarcinoma
mucinous cystadenocarcinoma
signet-ring adenocarcinoma
clear cell adenocarcinoma
Cytologic diagnostic features (sputum and bronchial washing)
Cell aggregates
Large eccentric pleomorphic nuclei
Prominent nucleoli
Abundant pale vacuolated cytoplasm
Cytologic diagnostic features (FNA and bronchial brushing)
Sheets, rosettes and acinar grouing, columnar cells and mucin production
Rounded nuclei
Prominent nucleoli
Abundant pale vacuolated cytoplasm
Clean or mucinous background
Differential diagnosis
Metastatic adenocarcinoma
Reparative/reactive bronchial epithelium
Creola bodies
Goblet cell hyperplasia
Reactive pneumocytes
Granulomatous inflammation
The cells of adenocarcinoma, except for poorly differentiated tumors, are more cohesive than those of squamous cell carcinoma. Poorly differentiated adenocarcinoma can be indistinguishable from large cell undifferentiated carcinoma with routine stains, but adenocarcinoma is positive for intracytoplasmic mucin.
Immunocytochemistry
Cytokeratin 7 +
Cytokeratin 5 –
Cytokeratin 20 –
Neuroendocrine markers +-
TTF-1 +
Adenocarcinoma:
Adenocarcinoma. Malignant cells with round nuclei and large prominent nucleoli forming a gland (acinar formation).Adenocarcinoma. Pleomorphic malignant cells with round nuclei, vesicular chromatin, and prominent nucleoli.Adenocarcinoma, poorly differentiated. Discohesive malignant cells with lack of gland formation, vesicular chromatin, and prominent nucleoli.
CAM 5.2TTF-1
FNA:
FNAFNAFNAFNA
Bronchial brush:
Bronchial brushBronchial brush
Squamous cell carcinoma. Numerous keratinized (orangeophilic) and non-keratinized malignant squamous cells dispersed in a background of keratinaceous debris (FNAB).Squamous cell carcinoma. Malignant keratinized squamous cells with marked pleomorphism and keratinaceous debris.Squamous cell carcinoma. Malignant heavily keratinized squamous cells (appearing orangeophilic) with marked pleomorphism in a background of necrotic cytoplasmic fragments.Squamous cell carcinoma. Note the extensive tissue necrosis, keratinaceous debris, and a single viable malignant keratinized cell (at 2 o' clock).Squamous cell carcinoma. An elongated "tadpole-shaped" malignant keratinized cell with heavily keratinized (orangeophilic) cytoplasm.
Occult carcinoma in situOccult carcinoma in situOccult carcinoma in situOccult carcinoma in situ
FNA moderately differFNAFNA well differHistologyFNAFNA well differFNA well differTransbronchial FNA
Bronchial brushBronchial brushBronchial brush
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