What is the cause of small red raised bumps on the scalp, forehead, between the breasts, and on the back in a patient suspecting yeast overgrowth?

Clinical Assessment of Small Red Raised Bumps on Scalp, Forehead, Chest, and Back

This presentation is most consistent with Malassezia folliculitis (formerly Pityrosporum folliculitis), a common yeast-driven follicular eruption that is frequently misdiagnosed as acne and inappropriately treated with antibiotics. 1

Key Diagnostic Features

The distribution pattern described—scalp, forehead, between breasts, and back—is classic for Malassezia folliculitis, which characteristically presents as monomorphic, pruritic papules and pustules in sebum-rich areas with high follicular density. 2 This differs from bacterial acne by its:

• Monomorphic appearance (uniform lesions rather than mixed comedones, papules, and cysts) 1
• Pruritus as a prominent symptom 2, 1
• Distribution in areas with high sebaceous gland density (face, scalp, upper chest, and back) 2
• Lack of response to antibiotics (often worsens with antibiotic use) 1

Immediate Diagnostic Steps

Obtain a potassium hydroxide (KOH) preparation from skin scrapings to visualize yeast and hyphae/arthroconidia, which provides rapid confirmation. 3 The specimen should be collected using a blunt scalpel to remove skin scale from the affected follicles. 3

Additional diagnostic modalities include:

• Dermoscopy to visualize follicular involvement 1
• Wood's lamp examination may show yellow-green fluorescence 1
• Fungal culture on Sabouraud agar if KOH is negative but clinical suspicion remains high (incubate for at least 2 weeks) 3

Critical Exclusion: Rule Out Immunocompromise

Before proceeding with routine treatment, determine if the patient has any immunocompromising conditions (neutropenia, chemotherapy, HIV, chronic corticosteroids, transplant recipient), as this transforms a benign condition into a potential medical emergency requiring blood cultures and aggressive tissue sampling. 4, 2 In immunocompromised patients, disseminated candidiasis can present as discrete pink to red papules (0.5-1.0 cm) on the trunk, though this is uncommon. 2

Treatment Algorithm

For Immunocompetent Patients:

First-line therapy: Oral antifungal agents are most effective for widespread involvement as described.

• Itraconazole 200 mg daily for 1-2 weeks is highly effective (87% mycological cure rate) 3
• Fluconazole 150-200 mg weekly for 2-4 weeks is an alternative 1
• Ketoconazole 200 mg daily has demonstrated efficacy by resolving follicular occlusion and reducing yeast overgrowth 5

Topical antifungals can be used for localized disease or as maintenance:

• Ketoconazole 2% shampoo or cream applied to affected areas 1
• Selenium sulfide 2.5% lotion 1

Critical Treatment Principles:

Continue treatment until mycological cure is documented, not just clinical improvement. 3 Stopping treatment based solely on visible improvement leads to rapid relapse, as follicular occlusion may persist even when inflammation resolves. 5

Follow-up with repeat KOH preparation or culture is recommended until mycological clearance is documented. 3

Common Pitfalls to Avoid

• Do not treat with antibiotics (tetracyclines, doxycycline), as this worsens the condition by further disrupting skin flora and promoting yeast overgrowth 1
• Do not use topical or oral corticosteroids alone, which will exacerbate fungal proliferation 6
• Do not stop antifungal therapy prematurely based on clinical appearance; relapses are common without complete mycological cure 3, 1
• Do not misdiagnose as acne vulgaris based solely on appearance; the pruritus, monomorphic lesions, and distribution should prompt consideration of fungal etiology 1

Pathophysiology Context

Follicular occlusion appears to be the primary event, with secondary yeast (Malassezia species) overgrowth occurring in the occluded follicles. 5 The beneficial effect of antifungals may be due to both direct antifungal action and effects on follicular occlusion itself. 5 This explains why mechanical factors (occlusive clothing, humidity, sweating) often precipitate or worsen the condition. 6

When to Biopsy

Biopsy is indicated if:

• Diagnosis remains uncertain after KOH preparation 4
• No response to appropriate antifungal therapy after 4 weeks 4
• Patient has any immunocompromising condition 4
• Lesions are rapidly progressive or becoming necrotic 4

Histopathology would show follicular inflammation with yeast organisms within the follicle, distinguishing this from other papulopustular eruptions. 2