Colon

Contributed by Aaron R. Huber, D.O.

A 65 year old man underwent screening colonoscopy. A small polypoid area was biopsied, as seen above. An immunostain for S100 protein is positive. What is the correct diagnosis?

1. Amyloid deposition
2. Granulomas
3. Mucosal Schwann cell hamartoma
4. Tactile corpuscle-like bodies (TCLBs)

D. TCLBs (formerly known as Wagner-Meissner corpuscles) are Schwannian mechanoreceptors found primarily in the skin and not normally present in the gastrointestinal tract (GIT). TCLBs in the GIT likely arise as a response to mucosal injury. TCLBs are incidentally discovered during endoscopy where they are most often associated with normal mucosa; however, they can also present as polyps. Histologically, TCLBs are seen as nodules within the lamina propria with lamellated or fibrillary eosinophilic cytoplasm. TCLBs are S100 protein positive, which helps distinguish them from some of their histologic mimics, including amyloid (Congo red+, S100-) and granulomata (CD68+, S100-). No treatment is required as TCLBs are benign.

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Reference: Tactile corpuscle-like bodies

Which of the following is true regarding tactile corpuscle-like bodies (TCLBs) in the gastrointestinal mucosa?

1. They always present as polyps on screening colonoscopy
2. They are neoplastic and require extensive resection
3. They are never associated with conditions that injure the mucosa such as inflammatory bowel disease
4. They may be confused with amyloid deposition or mucosal granulomata but are S100 protein positive

D. They may be confused with amyloid deposition or mucosal granulomata but are S100 protein positive. TCLBs are benign lesions that likely represent a reactive / reparative process as they are often associated with injured mucosa (B and C). TCLBs are most often incidental findings associated with an endoscopically normal mucosal appearance; however, in some cases they may appear as polyps (A). Histologically, TCLBs have a nodular architecture, composed of cells with abundant eosinophilic, fibrillary cytoplasm and peripherally placed small nuclei. These findings share morphologic characteristics with amyloidosis or granulomata, which can be distinguished by Congo red and CD68, respectively.

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Reference: Tactile corpuscle-like bodies