What does a fungal rash under the breasts look like in a female patient with diabetes, obesity, or immunosuppression?

Fungal Rash Under the Breasts: Clinical Appearance

A fungal rash under the breasts (candidal intertrigo) typically presents as erythematous, moist, macerated skin with characteristic satellite lesions in the inframammary fold. 1

Classic Morphology

• The primary lesion appears as bright red, erythematous skin with a moist, macerated appearance in the inframammary fold where skin-on-skin contact creates a warm, humid environment 1

• Satellite lesions are the hallmark feature—these are small, discrete pustules or papules that appear at the periphery of the main erythematous patch, distinguishing candidal infection from other causes of intertrigo 1

• The affected skin often has a well-demarcated border with the satellite lesions extending beyond the main area of involvement 1

• The rash is typically painful, pruritic, and may have a burning sensation due to the inflammatory response and skin breakdown 1

Critical Red Flags to Exclude Malignancy

Before attributing breast skin changes to fungal infection, you must actively exclude inflammatory breast cancer (IBC) and Paget's disease, as these malignancies frequently mimic infectious processes:

• If erythema and edema involve more than one-third of the breast skin, this mandates immediate workup for IBC rather than empiric antifungal treatment 2, 1

• Peau d'orange (dermal edema resembling orange peel) with a palpable border to the erythema is IBC until proven otherwise—this requires bilateral diagnostic mammogram with or without ultrasound before any antifungal therapy 2, 1

• Nipple excoriation, scaling, or eczematous changes suggest Paget's disease rather than simple intertriginous candidiasis and require punch biopsy 2, 1

• Any unusual skin changes around the breast require imaging to exclude malignancy before attributing symptoms to fungal infection 2, 1

High-Risk Patient Populations

In patients with diabetes, obesity, or immunosuppression, the clinical presentation may be more severe or atypical:

• Diabetic patients have increased prevalence of mucocutaneous candidiasis due to impaired neutrophil function, macrophage dysfunction, and altered cellular immunity 3, 4

• Immunosuppressed patients (HIV/AIDS with CD4+ <200, transplant recipients, those on corticosteroids or chemotherapy) may develop more extensive disease with deeper tissue involvement 5, 6

• Obese patients are particularly prone to intertrigo in skin folds due to persistent moisture and friction, creating an ideal environment for Candida overgrowth 5

Distinguishing Features from Other Fungal Infections

While candidal intertrigo is the most common fungal infection under the breasts, immunocompromised patients may develop invasive mold infections with dramatically different appearances:

• Invasive fungal infections (Aspergillus, Mucormycosis, Fusarium) in severely immunocompromised patients present as erythematous papules that become pustular, then develop central ulceration with an elevated border covered by black eschar—this is a medical emergency requiring immediate biopsy and systemic antifungal therapy 2

• These angioinvasive lesions may not be tender initially and are described as "cold to the touch," distinguishing them from typical bacterial cellulitis 2, 6

• Skin lesions from disseminated fungal infection occur most commonly on extremities but can appear anywhere, including inframammary areas, particularly at sites of previous IV lines or trauma 2

Diagnostic Confirmation

• KOH preparation of skin scrapings is the recommended first-line diagnostic test to confirm Candida infection by identifying characteristic pseudohyphal yeast forms 1, 7

• Culture is not routinely needed for uncomplicated intertrigo but should be obtained if symptoms persist after 7-14 days of appropriate therapy to identify non-albicans species with reduced azole susceptibility 1, 7

• Skin biopsy is mandatory if the clinical picture is atypical, if there is no response to appropriate antifungal therapy within 14 days, or if any features suggest IBC or Paget's disease 2, 1

Common Diagnostic Pitfalls

• Never assume breast skin changes are fungal without imaging—IBC and Paget's disease frequently present with erythema and skin changes that mimic infection 2, 1

• Persistent or progressive symptoms despite appropriate antifungal therapy warrant punch biopsy to exclude IBC or Paget's disease rather than simply switching antifungal agents 2, 1

• In immunocompromised patients, consider invasive mold infections if lesions develop necrotic centers or black eschars, as these require urgent systemic therapy and possible surgical debridement 2