Differential Diagnosis for Rash on Wrists and Stomach

Single Most Likely Diagnosis

• Contact Dermatitis: This is a common condition that occurs when the skin comes into contact with an irritant or allergen, leading to a rash. The location around the wrists and stomach, along with the presence of yellowish pus and intense itchiness, could be indicative of an allergic reaction to something like a metal (e.g., nickel in jewelry) or a substance in clothing or a belt. The yellowish pus might suggest a secondary infection.

Other Likely Diagnoses

• Eczema (Atopic Dermatitis): Characterized by itchy, inflamed skin, eczema can appear anywhere on the body, including the wrists and stomach. It often starts as a red, itchy patch that can become crusty or weepy if scratched.
• Scabies: A contagious skin infestation by the mite Sarcoptes scabiei, leading to intense itching and a pustular rash, which can appear in the described locations.
• Impetigo: A highly contagious skin infection that can cause red sores on the skin, which can burst and crust over, sometimes with a yellowish color, and is often accompanied by itching.

Do Not Miss Diagnoses

• Cellulitis: A bacterial skin infection that can cause redness, swelling, and warmth of the skin, and might be accompanied by pus. It requires prompt antibiotic treatment to prevent serious complications.
• Staphylococcal Scalded Skin Syndrome (SSSS): Although more common in infants, SSSS can occur in adults, especially those with compromised immune systems. It's caused by staphylococcal toxins that lead to widespread skin blistering and peeling, which can start with localized lesions.
• Erythema Multiforme: An immune-mediated disorder that can be triggered by infections or medications, leading to target-like lesions on the skin, which can sometimes appear on the wrists and trunk.

Rare Diagnoses

• Pemphigus: A group of autoimmune diseases that cause blistering of the skin and mucous membranes. While rare, pemphigus vulgaris could present with blisters that rupture and form erosions or crusts, potentially accompanied by itching.
• Bullous Pemphigoid: Another autoimmune blistering disease that primarily affects older adults, characterized by large blisters that can appear on various parts of the body, including the wrists and abdomen, and can be itchy.

Each of these diagnoses has distinct features, but overlapping symptoms can make differential diagnosis challenging, necessitating a thorough medical history, physical examination, and sometimes laboratory tests for accurate diagnosis and appropriate treatment.