Histopathological clues observed with hematoxylin and eosin staining in cases diagnosed with dermatophytosis

Histopathological clues observed with hematoxylin and eosin staining in cases diagnosed with dermatophytosis

B. Timur*, B. Lebe

*Department of Pathology, Dokuz Eylul University School of Medicine, Turkey

Background & objectives: Periodic Acid Schiff (PAS) stain, effective for detecting fungi's carbohydrate-rich cell walls, is standard for diagnosing dermatophytosis. Its use requires suspected fungal infection or observed histopathological clues. Our aim is to determine histopathological clues observed in skin biopsy diagnosed with dermatophytosis.

Methods: We examined cases diagnosed with dermatophytosis at Dokuz Eylul University Hospital from January 1, 2023, to April 1, 2024, excluding cases involving nails or mucous membranes. We analyzed the histopathological characteristics of 40 cases fitting these criteria, all of which were confirmed by demonstrating fungal hyphae using PAS staining. Features observed in the epidermis and dermis were recorded.

Results: The histopathological features observed in the epidermis are as follows: Spongiosis(10%none; 35%mild; 27,5%moderate; 15%extensive; 7,5%vesiculation),irregulary acanthosis(77.5%), sandwich sign in stratum corneum (62.5%), exocytosis of inflammatory cells(42,5%none; 37,5%lymphocytes; 10%neutrophils, 5%mixt), intraepidermal pustula (47,5%), empty spaces in the stratum corneum(45%), bacteria clusters (25%), parakeratosis(22.5%), epidermal dismaturation(12.5%), orthokeratosis(2,5%), fungal hyphea on H&E staining(5%), psoriasiform hyperplasia(2.5%). The histopathological features observed in the dermis as follows: In all cases, perivascular inflammatory cell infiltration is observed. Inflammatory cell types, including lymphocytes, atypical lymphocytes, eosinophils and neutrophils were present across different cases. Erthyrocyte extravasation (20%) and increased vascularity(65%) were also observed. Two cases couldn’t be examined for dermal properties because they only contained the stratum corneum.

Conclusion: Hyphae are hard to detect in H&E stained sections in skin biopsy. In our study, just two cases (5%) showed visible hyphae in the H&E staining. When we observed spongiosis, irregulary acanthosis, sandwich sign and intraepidermal pustula in epidermis, we keep in mind dermatophytosis in differential diagnosis in the skin biopsy. We suggest that applying PAS staining to cases exhibiting certain characteristics can help to confirm the diagnosis, even when not indicated in clinical or differential diagnoses.