Crescentic Hair Shaft Defects and Piedra-Like Lesions With Follicular Invasion in Northern Elephant Seals (Mirounga angustirostris).

CHSD and PLL are novel lesions in northern elephant seals associated with fungal and bacterial colonization.

This study provides the first formal histological and ultrastructural characterization of two previously undescribed hair shaft lesions in northern elephant seals (NES): crescentic hair shaft defects (CHSD) and piedra-like lesions (PLL). Researchers examined 51 NES (38 with skin lesions, 13 without) from two California locations, documenting gross findings and performing comprehensive histological analysis with special staining techniques. CHSD and PLL were identified in 61% of animals with skin lesions, predominantly in seals older than 7.5 months. Both lesions frequently co-occurred and were associated with suppurative luminal folliculitis (53%) and furunculosis (16%). Bacterial colonization was identified in 13 cases with CHSD, and fungal elements in seven cases. Panfungal PCR identified multiple fungal species including Cladosporium spp., previously reported in human white piedra infections. These lesions were exclusively observed in animals with dermatological disease and present in most cases of northern elephant seal skin disease (NESSD), suggesting a pathological association. While the exact etiology remains unclear, the authors propose that fungal and/or bacterial colonization of hair shafts may contribute to disease pathogenesis.

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