Cutaneous fibropapilloma in Egyptian-farmed gilthead seabream ( Sparus aurata ; Linnaeus, 1758)

In this study, three farmed Gilthead seabream exhibited tumor-like mass above the left pectoral fin. The mass measured 9 mm in length, 8 mm in width. Morphometrically, the mass was fleshy, raised, circumscribed, and rosy colored with grayish-white center. The affected fish showed poor growth with 280 g average body weight after 30 months rearing period. Internally, moribund fish exhibited pale kidney/liver, mottled spleen with remarkable visceral adhesions. The presumptive bacteriological and conventional biochemical assays revealed that fish were clinically infected with Photobacterium damselae subspecies piscicida . The histopathological picture of the tumor-like mass concurred with the standard cellular criteria of fibropapilloma. In brief, the epidermal papilloma was denoted by the remarkable hyperplasia of epidermis together with eosinophilic intracytoplasmic inclusion bodies and prominent mitosis in the hyperplastic cells. Ultimately, the proliferated dermal fibroblasts appeared whirling and elongated with spindle nuclei. Such pathological alterations have confirmed a typical form of dermal fibroma upon positively reacted with Masson’s trichrome stain. In the spleen, characteristic granulomatous reactions were observed especially in the area of melanomacrophage centers where the granuloma showed different developmental stages. The occurrence of skin tumors in farmed marine fish is an alarm for the critical impacts of the erratic usage of pesticides on marine aquaculture presenting a staggering prototype for the growing aquatic environmental pollution.