Dr  Sampurna Roy  MD

Histological features in a Normal Large Intestinal Biopsy:

MUCOSAL ARCHITECTURE:

There is increase in thickness of the mucosa from the caecum (500 micrometer) to the rectum (1000 micrometer).

Crypts are aligned parallel to the crypt bases. Crypts are straight and narrow and mostly unbranched separated by a thin rim of lamina propria. The distance between the crypts and the internal diameter of the crypts are constant.

Slight variation in crypt architecture, intercryptal spacing and occasional crypt branching may occur in normal biopsies.

Crypts are deeper in the rectum and sigmoid colon than in the proximal part of the colon.

SURFACE EPITHELIUM:

Composed of absorptive (tall columnar), goblet and endocrine cells.

Ratio of the number of tall columnar cells to goblet cells is 4:1.

Paneth cells are usually present in the caecum & proximal colon (usually confined to the crypt bases).

Presence of Paneth cells more distally indicates metaplastic change seen in chronic infection.

The proliferative zone in the base of the crypt is composed of low cuboidal stem cells.

Surface epithelial cells overlying lymphoid follicles are more cuboidal and compactly arranged rather than columnar cells elsewhere (this should not be mistaken for dysplastic cells in ulcerative colitis).

LAMINA PROPRIA:

Loose, areolar connective tissue which appears highly cellular due to the presence of chronic inflammatory cells in the superficial part of the lamina propria.

Predominantly plasma cells are present together with scattered lymphocytes (mostly T-cells).

Inflammatory cells in the deeper part and separation of crypt bases from muscularis mucosae by a band of plasma cells and lymphocytes is indicative of chronic inflammatory bowel disease.

 Occasional neutrophils are present in the lamina propria of normal colonic biopsies.

Neutrophils in the surface and crypt epithelium is indicative of a pathological process.

Lymphoid follicles of B-lymphocytes are present in colonic mucosa and may extend through muscularis mucosae into submucosa.

At these points mucosal crypts extend into the mucosa forming lymphoid-glandular complexes (should not be mistaken for a pathological process).

MUSCULARIS MUCOSAE:

 Thin smooth muscle layer (inner circular and outer longitudinal layer).

SUBMUCOSA:

There is loose connective tissue with collagen and elastic fibres. Meissner's plexus of autonomic nerve fibres with ganglion cells are present. Detailed examination of this layer is necessary in Hirschsprung's disease.
 

Image I: Straight, narrow, parallel-sided crypts arise from above muscularis mucosae and open on the surface. Image II: Surface and upper crypt epithelium. A: Thin sub-epithelial collagen plate (upto 3 micrometer thick). Image III: Mucin secreting goblet cells from proximal colon. Cells stained magenta with PAS/AB. Image IV: Mucin secreting goblet cells from distal colon. Cells stained blue with PAS/AB. [Sialomucin-PAS(+) AB(+) & Sulphomucin- PAS(-) AB(+), High iron diamine (+). Distal large bowel has more sulphomucin and proximal colon has more sialomucin]. Image V:A: Crypt, B: Lamina propria, C: Muscularis mucosae , D: Submucosa: 1:  Goblet cell   2: Columnar cell   3: Stem cell  4: Blood vessel  5:  Subepithelial collagen plate    6: Muciphages  7:Lymphocytes www.histopathology-india.net/GIPath.htm Soft Tissue Pathology; Myxoid Tumours of Soft Tissue ;  Classification of Soft Tissue Tumour;  Gross examination of soft tissue specimen ;  A practical approach to histopathological reporting of soft tissue tumours ;  Grading of soft tissue tumours ; Lipomatous tumours ;Neural tumours ; Myogenic tumours ;Vascular tumours ; Fibroblastic/ Myofibroblastic tumours ; Myofibroblastic tumours ;  Fibrohistiocytic tumours ; ChondroOsseous tumours ; Soft TissueTumours of Uncertain Differentiation ; Notochordal Tumour -Chordoma ;Extra-adrenal Paraganglioma ; Gastrointestinal Stromal Tumour ;