Dermatophytic granuloma: causes, symptoms, diagnosis, and treatment

Dermatophytic granuloma, also known as Majocchi granuloma or granuloma trichophyticum, is an infection of the skin and subcutaneous tissue caused by dermatophytes.


Causes

The most common pathogens are trichophyton rubrum, microsporum canis, and aspergillus fumigatus, and trichophyton rubrum accounts for appropriately 50%. Dermatophytes are usually confined to the stratum corneum, but they can be more aggressive and invade the superficial dermis, causing granulomatous reactions. Patients are often using topical strong corticosteroids or systemic immunosuppressive agents.


Signs and Symptoms

According to the clinical presentations and immune status of patients, the disease can be divided into perifollicular granuloma and subcutaneous nodular granuloma, which progress from initial suppurative folliculitis to extensive granulomatous infiltration.

Perifollicular granuloma is usually seen in healthy individuals, and occurs mostly after trauma, such as shaving or stabs, or long-term topical corticosteroids. The illness can be misdiagnosed as eczema or secondary to eczema after long-term topical glucocorticoids. The clinical features are superficial pustular perifolliculitis.

Figure 1 multiple perifollicular nodules

Figure 2 red papules, plaques, and nodules on the face (A) and scalp (B), hyphae and spores (C and D) in PAS stain, after use of glucocorticoids

Figure 3 erythema, papule, and nodules, after use of glucocorticoids

Subcutaneous nodular granuloma is common in immunocompromised individuals, such as patients receiving immunosuppressive therapy due to leukemia, lymphoma, autoimmune disease, organ transplantation, or other malignant tumors, can occur in any pilose area, and is characterize by chronic erythema, hard plaques, and subcutaneous nodules

Figure 4 erythema and reddish brown nodules in the dorsal feet


Diagnosis

If patients with papular or pustular plaques, especially when local or systemic immunosuppression is present, this disease should be suspected.

Definitive diagnosis requires the detection of dermatophytes and presence of perifollicular granulomatous inflammation. Fungal spores and hyphae are often detected in hair follicles and dermal granuloma. However, diagnosis cannot be excluded even if the results of microscopic examination or culture of scales or purulent secretions are negative. Periodic acid Schiff (PAS) stain can assist in the diagnosis.

Figure 5 histopathology, perifollicular granuloma (A), hyphae in high magnification microscopy (B), spores in PAS stain (C), spores in immunofluorescence (D)


Treatment

Treatment regimen is oral antifungals, such as terbinafine, itraconazole, and griseofulvin, for 4 - 8 weeks. Although topical antifungal agents cannot enter the deep skin, they are often used in adjuvant treatment.