Does the original in-service diagnosis matter if a later provider says it was actually a different condition?

For VA disability compensation, the label given to a condition at the time of an in-service diagnosis is not the deciding factor. What matters legally is whether you meet the three elements of service connection under 38 CFR 3.303 and 38 USC 1110: (1) a current diagnosis, (2) evidence of an in-service event, injury, or disease, and (3) a medical nexus linking the two. The specific name written on a decades-old chart entry is evidence toward element two, not a binding determination of what condition you actually had.

When the in-service treatment records show skin symptoms consistent with both seborrhea and psoriasis, and subsequent dermatologists — including your current provider — believe the correct diagnosis was psoriasis all along, that supports an argument that the same disease process has been continuous since service, just mislabeled at the time. VA adjudicators are supposed to look at the underlying symptomatology and clinical findings recorded in service, not just the diagnostic code a clinician wrote decades ago. A misdiagnosis does not erase the fact that a chronic skin condition began on active duty if the objective findings match.

The strongest way to support this kind of claim is a current nexus opinion, ideally from your treating dermatologist, explicitly stating that in their medical opinion the symptoms documented in the service treatment records represent the same psoriasis they are now treating, and that the original seborrhea diagnosis was more likely than not an error given the presentation. A well-reasoned opinion addressing why the in-service findings are more consistent with psoriasis than seborrhea carries significant weight, especially if it discusses the chronic, relapsing-remitting nature of psoriasis and any continuity of flare-ups in the years between service and the current diagnosis.

If you already have a denial on file for seborrhea or an earlier claim, you may want to file a supplemental claim (VA Form 20-0995) with this new nexus evidence rather than starting from scratch, since it directly addresses the reason for any prior denial. If this is a first-time filing, submit the claim for psoriasis and clearly lay out the misdiagnosis argument with supporting private treatment records.

As a concrete next step, ask your current dermatologist to write a nexus letter specifically addressing why the in-service symptoms were more likely psoriasis than seborrhea, and submit that letter along with your service treatment records and any supplemental claim paperwork.