Hello and welcome to HCM,
A patch on palms can occur due to many causes.
Viral infection or primary skin infection
are one of the common causes for such a rash.
Is the rash associated with itching?
Rash associated with itching can be due to fungal infection
A number of skin diseases are associated with spreading rash of this kind.
Viral infection, psoriasis
, para-psoriasis, eczema are some of the disease processes which can cause rash of this type.
A skin biopsy
is required to diagnose skin lesion causing the rash.
Thanks and take care
Dr Shailja P Wahal