A literally blinded trial of palpation in dermatologic diagnosis

As an adjunct to visual inspection, dermatologists routinely palpate the skin during clinical examination. The value of palpation in isolation is unproven.

To determine whether palpation alone could distinguish between two common dermatoses, atopic dermatitis and plaque psoriasis, a cohort of 16 patients were examined by a dermatologist using touch alone, with screens to prevent visualisation of the lesions.

The diagnosis was correctly made in 14 of 16 cases (P = .012).

Patients were not consecutive as availability of the dermatologist and nursing staff was required, and several exclusion criteria applied. There was no formal power calculation. The study aimed to prove a concept about dissociating sensory modalities and does not prove that palpation would necessarily have provided "added value" to a visual diagnosis in the cases selected.

This study demonstrates that dissociation between sensory inputs that are usually concurrent (in this case, visual and tactile) is a feasible experiment in dermatology, and that such dissociation did not remove the diagnostic input of the sole sensory modality that was permitted-in this case, confirming that palpation alone does have some importance in dermatologic diagnosis. It may explain some of the reservations about accuracy of teledermatology diagnoses of dermatoses, where palpation is not possible.