Contact Dermatitis: This is a common condition that can occur when the skin comes into contact with an irritant or allergen, leading to inflammation. Given the localized nature of the issue, from the lower abdomen to the legs, it's plausible that the skin is reacting to something it has come into contact with in this specific area.

Eczema (Atopic Dermatitis): A chronic condition characterized by dry, itchy, and inflamed skin. It can appear anywhere on the body and might be limited to the lower abdomen and legs due to various factors, including genetic predisposition and environmental triggers.
Psoriasis: An autoimmune condition that speeds up the life cycle of skin cells, causing cells to build up rapidly on the surface of the skin. The lesions can appear anywhere but often affect the lower back, elbows, and legs.
Keratosis Pilaris: A harmless condition that causes small, rough patches on the skin, often on the arms, legs, buttocks, and cheeks. It could be considered if the skin issue presents with characteristic rough, sandpapery patches.

Deep Vein Thrombosis (DVT): Although DVT primarily presents with swelling, pain, and discoloration of the leg, it's a critical condition that requires immediate medical attention due to the risk of pulmonary embolism. Skin changes can sometimes be part of the presentation.
Cellulitis: A bacterial skin infection that can cause redness, swelling, and warmth of the skin. It's essential to diagnose and treat promptly to prevent serious complications.
Lymphoma: Certain types of lymphoma can cause skin lesions. While rare, missing a diagnosis of lymphoma could have severe consequences.

Erythema Ab Igne (EAI): A rare condition caused by prolonged exposure to heat, leading to reticulated erythema, hyperpigmentation, and potentially telangiectasias. It's more common in individuals who use heating pads or laptops on their laps for extended periods.
Necrobiosis Lipoidica: A rare condition characterized by necrotic, granulomatous lesions typically on the shins. It's associated with diabetes but can occur in non-diabetic individuals as well.
Scleroderma: A group of diseases that result in the hardening and tightening of skin and connective tissues. While systemic scleroderma can affect internal organs, localized scleroderma (morphea) can cause skin thickening and may present in a limited area such as the lower abdomen and legs.