“Thumb printing sign” on barium study is a feature of-
**Core Concept**
The "thumb printing sign" is a radiological feature observed on barium studies, which is indicative of a specific gastrointestinal disorder. This sign is characterized by the presence of multiple, rounded, and closely spaced filling defects or "thumb prints" within the intestinal lumen.
**Why the Correct Answer is Right**
The thumb printing sign is a classic radiological feature of **invasive carcinoma of the colon**. These lesions cause the mucosa to become thickened and edematous, resulting in the formation of small, rounded filling defects that give the appearance of "thumb prints" on barium studies. The pathophysiology behind this sign involves the invasion of cancer cells into the intestinal wall, leading to mucosal thickening and distortion.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because the "thumb printing sign" is not typically associated with **diverticulosis**, which is characterized by the presence of multiple, small, outpouchings of the intestinal wall.
* **Option B:** This is incorrect because **Crohn's disease** may cause various radiological abnormalities, including strictures, fistulas, and cobblestoning, but it is not typically associated with the "thumb printing sign".
* **Option C:** This is incorrect because **infectious colitis**, such as that caused by amoebiasis or bacillary dysentery, may cause mucosal inflammation and ulceration, but it is not typically associated with the "thumb printing sign".
**Clinical Pearl / High-Yield Fact**
The thumb printing sign is a classic radiological feature of invasive carcinoma of the colon, and its presence should prompt further investigation, including endoscopy and biopsy, to confirm the diagnosis.
**Correct Answer: D. Invasive carcinoma of the colon.**