I think that several options are available...but considering the breed...I just gave this information to another client...maybe you should think about this as a question for your vet...as well as other things I listed.
Zinc responsive dermatosis of Siberian Huskies and Alaskan malamutes have a primary syndrome. Alaskan malamutes/Huskys can have a genetic defect affecting the absorption of zinc from the intestines. Thus, the condition can occur even while the dog is on a well-balanced commercial food.
Zinc-responsive dermatosis may be precipitated by stress, estrus, and GI disorders. Diets high in calcium and phytate (plant derived protein) may aslo precipitate the disorder by binding zinc in the GI tract.
Lesions usually develop in dogs in young adulthood. They can include alopecia (hairloss), erythema (reddening of the skin), scaling and crusting involving the face, nose,head, scrotum and legs. Lesions often can encircle the mouth, chin, eyes, ears, prepuce, and vulva, but any lesions found in these breeds should be considered a rule out. Thick crusts may be found on the elbows and other pressure points of the body. The footpads may be hyperkeratotic. Haircoat is generally dull and dry.
If lesions are present and diagnosis and treatment recommended.
Also..the immune system "thing" doesn't diagnose anything. There are immune mediated diseases, like lupus, that start with lesions on the bridge of the nose and no amount of sun protection will change an immune mediated process.
You can try sun issues, but I would be considering other things. If your vet is reluctant to do anything else, you may want to visit a different vet for a second opinion OR ask for a referral to a vet dermatologist. Lastly...a thyroid check may be indicated as well.
As far as $$ you may want to start with the least expensive treatment of sunblock first...