I assume you are worried about dermomyositis with lung cancer? Has he got any other symptoms associated with dermomyositis like Gottrons papules or muscle weakness etc?
You can get dermomyositis without it being from a malignant source. Also rosacea and dermomyositis rashes can look very similar to the naked eye and needs dermatoscopy to differentiate so given he has seen 2 specialists, one of which is a specialist dermatologist (and he has no other symptoms presumably?) could it maybe be simply rosacea and nothing more serious given he has no other symptoms and it’s been going on for a while?
Blood tests are not usually offered with rashes straight away in GP and the more unusual bloods requested for dermomyositis are not usually done in GP anyway. If the dermatologist suspected this a skin biopsy would have been arranged.
With respect to your ENT friend given he has only gone off pictures and your description it’s quite unprofessional of him to cast aspersions on the management of other doctors.
As far as the letter writing and referral thing. Doctors are not allowed to breach confidentiality and cannot refer on third party discussions usually even if that third party is a close relative if the patient themselves had capacity. If you have not been to the GP appointments with him then you have no idea what has been discussed between them as the communication between you and your DH sounds limited so I expect he hasn’t told you much detail so the ethics and suggestion by GMC referrals etc is irrelevant.
I do genuinely feel for you, your anxiety is almost palpable in your posts
. You need to sit your husband down and be honest with how it is affecting you, you will end up making yourself unwell with the stress if there is no resolution.
(And to the poster who said GPs are there to provide a Primary Care Triage Service, no we are bloody well not. We are specialists in general practice. IMO we should be called Consultants in Primary Care. We have to know a lot about everything, we are not just a referral service).
No doubt I will get pilloried for what I have said but TL;DR be honest with your husband OP, for your own sanity