Differential Diagnosis for Rash Under Arm
The patient presents with a rash under the arm, characterized by pinpoint centers with red round areas around them, accompanied by mild itchiness, sensitivity to touch, and occasional burning sensations. Given the symptoms, the following differential diagnoses are considered:
- Single most likely diagnosis
- Contact Dermatitis: This is a common condition that can cause a rash with red, itchy, and burning sensations, especially in areas like the underarm where skin folds can trap irritants. The presence of pinpoint centers could be indicative of an allergic or irritant reaction.
- Other Likely diagnoses
- Eczema (Atopic Dermatitis): Eczema can cause red, itchy, and sensitive skin, and it often appears in the folds of the skin, such as under the arms. The pinpoint centers could represent areas of intense inflammation.
- Folliculitis: This condition involves inflammation of the hair follicles and can present with small, red, itchy bumps, which might fit the description of pinpoint centers with red round areas.
- Intertrigo: A condition that occurs due to skin-on-skin friction, often in moist areas like the underarms, leading to redness, itching, and burning sensations.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cellulitis: Although less likely given the description, cellulitis is a bacterial infection of the skin that can cause redness, swelling, and warmth, and can be serious if not treated promptly.
- Lymphoma: Certain types of lymphoma can cause skin lesions, although this would be a rare presentation and typically accompanied by other systemic symptoms.
- Rare diagnoses
- Pityriasis Rosea: A condition that can cause a rash with a characteristic "herald patch" followed by smaller patches, sometimes with a burning sensation, though it's less common under the arms.
- Granuloma Annulare: A benign condition that can cause ring-shaped lesions, though it's not typically itchy or burning and doesn't usually present under the arms.
Each diagnosis is considered based on the combination of symptoms described, including the appearance of the rash, its location, and the sensations experienced by the patient. The absence of exposure to new substances or environments helps to narrow down the differential but does not rule out conditions that could be triggered by internal factors or pre-existing sensitivities.