In vivo devices, systems and methods for in vivo immunoassay include inserting into a patients body lumen an in vivo diagnostic device comprising a housing. The housing of the device comprises a chamber, and a chromatography strip for immunoassay of a body lumen substance. The housing may further comprise a casing for the chromatography strip. The casing may comprise a first opening to allow entrance of in vivo liquids into the casing and a second opening into the chamber. The housing may further comprise a sensor to sense a property of the chromatography strip. Following insertion of the device into the patients body, a sample is collected and the immunoassay is performed in vivo in areas of pathological lesions for a predetermined period of time. An in vivo image may be acquired or other data such as colorimetric or intensity data may be obtained from the chromatography strip.