Folliculitis: This condition is characterized by inflammation of the hair follicles, often due to bacterial infection, and can present as multiple small pustules. It's common in areas with high sebaceous gland activity and can be exacerbated by friction, sweat, and obesity, making it a likely diagnosis for an elderly, overweight woman.

Acne Vulgaris: Although more common in younger individuals, acne can persist or recur in older adults, especially in women due to hormonal changes. The presence of multiple small pustules, especially on the face, chest, or back, could suggest acne.
Pompholyx (Dyshidrotic Eczema): This condition presents with small, itchy blisters or pustules on the hands or feet, often associated with stress, allergies, or exposure to certain metals. While not exclusively related to obesity, the stress and potential for skin barrier disruption in an elderly, overweight individual could contribute to its development.
Intertrigo: A skin condition that occurs in warm, moist areas of the body where skin folds together, such as the groin, underarms, or beneath breast tissue. It can lead to a rash and pustules due to fungal or bacterial infections, which are more common in obese individuals due to increased skin folds and moisture.

Cellulitis: An infection of the skin and subcutaneous tissues, which can start as a small, red, painful area and spread. While it typically does not present with multiple small pustules initially, it can evolve to include them, especially if there's a delay in treatment. It's crucial to identify and treat promptly to avoid serious complications.
Necrotizing Fasciitis: A severe infection that destroys the tissue under the skin, including fat and the tissue covering the muscles (fascia). Early signs can be subtle and might include a small, painful area of skin that quickly progresses. Although rare, it's a medical emergency that requires immediate attention.
Staphylococcal Scalded Skin Syndrome (SSSS): Caused by staphylococcal toxins that typically affect infants and young children but can rarely occur in adults, especially those with compromised immune systems. It presents with widespread blistering and peeling of the skin, which could initially be mistaken for a pustular rash.

Subcorneal Pustular Dermatosis: A rare skin condition characterized by the sudden onset of multiple, small, sterile pustules, primarily on the trunk, that can be associated with various systemic diseases, including malignancies and inflammatory conditions.
Generalized Pustular Psoriasis: A rare and severe form of psoriasis that presents with widespread pustules across the body, often accompanied by systemic symptoms like fever and malaise. It can be life-threatening if not recognized and treated appropriately.
Sweet Syndrome (Acute Febrile Neutrophilic Dermatosis): Characterized by the sudden onset of fever, leukocytosis, and tender, erythematous, well-demarcated papules and plaques that may evolve into pustules, often associated with underlying systemic diseases or infections.