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Friday 23 November 2018


Definition: Insulinoma-associated protein 1 is a protein that in humans is encoded by the INSM1 gene.

Insulinoma-associated 1 (INSM1) gene is intronless and encodes a protein containing both a zinc finger DNA-binding domain and a putative prohormone domain. This gene is a sensitive marker for neuroendocrine differentiation of human lung tumors.


Merkel cell carcinoma (MCC) is an extremely aggressive skin cancer that must be distinguished from other basaloid cutaneous neoplasms that have different treatments and prognoses.

Insulinoma-associated protein 1 (INSM1) immunohistochemistry is a sensitive nuclear marker of neuroendocrine differentiation.

INSM1 staining cannot distinguish MCC from metastatic extracutaneous neuroendocrine carcinoma.

INSM1 holds promise as a neuroendocrine marker that can distinguish MCC from its mimickers in the skin and improve detection of sentinel lymph node metastases.

Paywall references

- INSM1 is More Sensitive and Interpretable than Conventional Immunohistochemical Stains Used to Diagnose Merkel Cell Carcinoma. Lilo MT, Chen Y, LeBlanc RE. Am J Surg Pathol. 2018 Aug 4. doi : 10.1097/PAS.0000000000001136 PMID: 30080705