# Diascopy

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**Diascopy** is a test for [blanchability](/source/Blanch_(medical)) performed by applying pressure with a finger or glass slide and observing color changes.[1][2][3][4]

It is used to determine whether a [lesion](/source/Lesion) is [vascular](/source/Blood_vessel) ([inflammatory](/source/Inflammation) or [congenital](/source/Congenital_disorder)), nonvascular ([nevus](/source/Nevus)), or [hemorrhagic](/source/Hemorrhagic) ([petechia](/source/Petechia) or [purpura](/source/Purpura)). Hemorrhagic lesions and nonvascular lesions do not [blanch](/source/Blanch_(medical)) ("negative diascopy"); inflammatory lesions do ("positive diascopy"). Diascopy is sometimes used to identify [sarcoid](/source/Sarcoidosis) skin lesions, which, when tested, turn an apple jelly color.

Diascopy with [glassware](/source/List_of_glassware) is used as a method of diagnosing bacterial meningitis, as the rashes caused by the illness are [non-blanching](/source/Non-blanching_rash).[5]

## References

1. Marks, James G; Miller, Jeffery (2006). *Lookingbill and Marks' Principles of Dermatology* (4th ed.). Elsevier Inc. Page 29. ISBN 1-4160-3185-5.

1. Goldman, L.; Plotnick, H.; Balinkin, I. (May 9, 1957). "Investigative and clinical studies with diascopy in dermatology". *Archives of Dermatology*. **75** (5): 699–705. [doi:10.1001/archderm.1957.01550170067012](https://doi.org/10.1001/archderm.1957.01550170067012). [PMID 13410135](https://pubmed.ncbi.nlm.nih.gov/13410135)

1. D, Pérez-López; M, Peña-Cristóbal; EM, Otero-Rey; I, Tomás; A, Blanco-Carrión (October 1, 2016). "Clinical value of diascopy and other non-invasive techniques on differential diagnosis algorithms of oral pigmentations: A systematic review". *Journal of Clinical and Experimental Dentistry*. **8** (4): e448–e458. [doi:10.4317/jced.53005](https://doi.org/10.4317/jced.53005). [PMC 5045694](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5045694). [PMID 27703615](https://pubmed.ncbi.nlm.nih.gov/27703615)

1. Rudd, M.; Eversole, R.; Carpenter, W. (March 9, 2001). "Diascopy: a clinical technique for the diagnosis of vascular lesions". *General Dentistry*. **49** (2): 206–209. [PMID 12004702](https://pubmed.ncbi.nlm.nih.gov/12004702)

1. ["Meningitis Glass Test - Meningitis Rash Test"](https://www.meningitisnow.org/meningitis-explained/signs-and-symptoms/glass-test/). *Meningitis Now*. Retrieved 2025-05-10.

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