Allergic contact dermatitis can be linear (e.g., from poison ivy), but phytophotodermatitis is a phototoxic reaction, not an allergic one, and requires sunlight for the reaction to occur.
This is a rare, linear, "whip-lash" eruption associated with bleomycin chemotherapy or shiitake mushroom ingestion, a different specific cause.
A simple sunburn would be a confluent erythema in all sun-exposed areas, not the bizarre, streaky, or drip-like patterns that result from contact with a photosensitizing plant.
