Pain and swelling in the plantar area under the first metatarsophalangeal joint during weight-bearing points to inflammation around the sesamoid bones. The sesamoids sit under the big toe and endure the push-off load in gait; repetitive stress or overuse can inflame the surrounding soft tissues, producing focal tenderness at the plantar surface and swelling without prominent nerve symptoms. That combination—weight-bearing–related pain with plantar soft-tissue swelling and no neurological signs—fits sesamoiditis well. Freiberg disease would typically involve an avascular necrosis of a metatarsal head (often the second), causing focal joint pain and stiffness rather than plantar soft-tissue swelling at the first MTP joint. Morton neuroma presents with neuropathic pain and paresthesias between the toes, and is characterized by neural signs rather than localized plantar swelling. Anterior tarsal syndrome involves nerve entrapment that yields dorsiflexion weakness or sensory changes on the dorsum of the foot, not the plantar aspect around the sesamoids.