Uncommon hepatic macrophagic foamy‐cell nodules in Iberian barbel (Luciobarbus bocagei Steindachner, 1864) from the Vizela River (Portugal)

• Published in: Microscopy research and technique 2019-07, Vol.82 (7), p.1127-1135
• Main Authors: Carrola, João S., Fontainhas‐Fernandes, António, Rocha, Eduardo
• Format: Article
• Language: English
• Subjects: biomarkers; Connective tissues; Fish; Glycoproteins; Hepatocytes; histopathology; Industrial areas; Iron; Lesions; Liver; Macrophages; Melanin; Nodules; Parasites; Rivers; Septum; toxicology; Water pollution; Water quality
• ISSN: 1059-910X; 1097-0029
• DOI: 10.1002/jemt.23260

The main intent of this work (after the by chance finding, in archived histological slides) is to characterize one previously non‐described liver lesion of the Iberian barbel from the Vizela River (Portugal). This ran through a textile and dyeing industrial region. The lesion type was made of groups of foamy cells (presumptive macrophages), which appear either as a “smaller non‐nodular form,” without a connective tissue capsule and displaying an irregular profile, or as a “bigger nodular form,” presenting a thin capsule and a circular profile. The nodular forms could appear multi‐layered, resembling “cross‐sectioned onions”. The lesions number, dimension, and structural complexity were greater in bigger fish, appearing only after a history of poor water quality. In extreme cases, the lesions slightly protruded the liver surface. Special histological staining proved the connective tissue nature of the capsule (and its eventual septa), the presence of proteins, glycoproteins, lipofuscin, melanin, iron (putative hemosiderin), and copper, in a variable number of foamy cells within the lesions. At times, degenerating hepatocytes appeared at the border of the lesions. It is proposed that this lesion type incorporates both macrophages and degenerating hepatocytes, looking as one (unpublished) form of a macrophage aggregate. The term “foamy‐cell nodules” was advanced for this abnormality. The lesion could have been induced by pollution, because: no parasites were ever associated with the lesion; there was co‐existence of the lesion with a water quality status scored as “bad”; such lesion neither existed in fish sampled after mitigation and remediation measures nor in reference fish. Unusual liver lesions were found in Iberian barbel only from a much‐polluted river. The striking lesions were bigger circular nodular forms, with a thin capsule and septa. These “foamy‐cell nodules” integrate macrophages and degenerating hepatocytes.