Pathology Flashcards
- What is the difference between the tissue obtained by fine needle aspiration and a core biopsy?
Fine needle aspiration and the core biopsy differ in their procedure. In a fine needle aspiration a thin needle and stylet is used to aspirate a small amount of tissue and/or fluid from the area under investigation. In a core biopsy a large bore needle is used to collect larger tissue sample from the area of investigation and requires the use of local anaesthetics.
The key difference is that an FNA only collects a small tissue fragment whilst a core biopsy collects larger tissue fragments with preserved architecture. This allows for histopathological assessment of the core biopsy sample whilst a fine needle aspiration sample can only be used for cytological assessment.
Core biopsys are effective in distinguishing invasive and non invasive lesions whereas FNA aspirations are not.
Fine needle aspirations can lead to fewer complications than a core biopsy but is subject to more sampling problems and has a slighltly lower sensitivity.
- What are the differences in pathology between UC and Crohns?
Chrons disease and ulcerative colitis can vary in pathology on a macroscopic and microscopic level.
Chrons disease can affect any part of the digestive tract from the mouth to the anus and most commonly affects the distal ileum and proximal colon , whilst Ulcerative colitis affects more commonly affects the colon and rectum.
Ulcerative colitis generally starts in the rectum and spreads proximally in a continuous fashion, whereas, CD can have a discontinuous distribution and this can be seen as skip lesions.
Crohn’s disease is also more likely than ulcerative colitis to cause fistula, benign fibrous strictures, and perianal disease.
Ulcerative colitis affects only the mucosal layer whereas CD has transmural involvement.
In ulcerative colitis there is widespread irregular superficial ulceration with or without pseudopolyps but in chrons disease there is fissuring, transmural ulceration causing a cobblestone appearance.
Clinically diarrhea and rectal bleeding are a lot more common in ulcerative colitis compared to CD.
In CD granuloma formation is characteristic but not always present but in UC granuloma formation is absent.
