Squamous/Adenosquamous Carcinoma, Gallbladder

 Metaplasia → dysplasia → carcinoma sequence



• Progression from preexisting adenocarcinoma
image Considered “metaplastic carcinoma” like that in breast

• Gallstones present in 40-68% of cases




Clinical Issues




• 1-12% of all gallbladder carcinomas
image Pure squamous cell carcinoma: 0.5-3.0%

• Worse prognosis than conventional gallbladder adenocarcinoma stage by stage


Macroscopic




• White-tan, firm or friable, intraluminal fungating mass

• Diffuse thickening and induration of gallbladder wall

• May involve adjacent organs, including liver, colon, stomach, duodenum, omentum, pancreas, extrahepatic bile ducts, hepatic arteries


Microscopic




• Squamous cell carcinoma
image Composed entirely of squamous component

image Spindle cells may predominate in poorly differentiated/sarcomatoid cases

• Adenosquamous carcinoma has both malignant glandular and squamous components
image Glandular component: Any amount

image Squamous component: ≥ 25% of tumor volume


Top Differential Diagnoses




• Metastatic squamous cell carcinoma

image
Squamous Cell Carcinoma
This primary squamous cell carcinoma was resected from a 84-year-old man who presented with acute cholecystitis. A 4.6-cm intraluminal mass was found in the fundus in cholecystectomy specimen. Extensive sampling did not reveal glandular component. Note the presence of partially preserved gallbladder mucosa image over tumor.


image
Keratinization
This case of primary squamous cell carcinoma of the gallbladder shows islands of malignant cells with prominent keratinization image .

image
Squamous Metaplasia
The gallbladder mucosa adjacent to invasive squamous cell carcinoma shows a focus of squamous metaplasia with dysplastic changes image. Note that the focus is flanked by preserved gallbladder mucosa showing reactive changes image .

image
Adenosquamous Carcinoma
This primary adenosquamous carcinoma of the gallbladder shows squamous cell component image adjacent to a malignant gland image .


TERMINOLOGY


Definitions




• Malignant epithelial neoplasms of gallbladder composed of either pure squamous component or both squamous and glandular components


ETIOLOGY/PATHOGENESIS


Histogenesis




• Neoplastic transformation from squamous metaplasia of gallbladder mucosa
image Metaplasia → dysplasia → carcinoma sequence

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Apr 20, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Squamous/Adenosquamous Carcinoma, Gallbladder

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