Chromatoforoma’s bij reptielen

Abstract

Neoplasieën van de pigmentcellen of chromatoforen bij reptielen worden naargelang hun oorsprong geclassificeerd als melanoforoma’s, iridoforoma’s, xantoforoma’s, erytroforoma’s of gemengde chromatoforoma’s. In tegenstelling tot wat oorspronkelijk verondersteld werd, komen deze primaire, cutane neoplasieën regelmatig voor bij in gevangenschap gehouden reptielen. Melanoforoma’s en iridoforoma’s worden het meest frequent vastgesteld. Een definitieve diagnose van chromatoforoma’s wordt bekomen door middel van histologisch onderzoek. Aanvullend is immunohistochemie of elektronenmicroscopie soms noodzakelijk om chromatoforoma’s onderling te differentiëren. Complete chirurgische excisie wordt beschouwd als de voorkeursbehandeling. Vanwege de uitgesproken maligniteit en neiging tot metastasering is de prognose van chromatoforoma’s bij reptielen over het algemeen echter sterk gereserveerd. Een vroegtijdige en correcte diagnose van deze neoplastische aandoening bij reptielen is daarom van primordiaal belang. In dit artikel wordt een overzicht gegeven van de huidige kennis omtrent het voorkomen, het biologisch gedrag, de pathogenese en de diagnostische en therapeutische benadering van chromatoforoma’s bij reptielen met de nadruk op melano- en iridoforoma’s.

Chromatophoromas in Reptiles

“…Melanophoromas and iridophoromas are most common, with few reports of mixed chromatophoromas, xanthophoromas, and amelanotic or non-pigmented chromatophoromas [ 8 , 11 , 12 , 13 , 17 , 18 ]. Of the different reptilian orders, they are most frequently described in squamata with few reports in testudines (chelonia) and no reports in crocodilia or rhynchocephalia [ 9 , 11 , 12 , 13 , 14 , 19 , 20 , 21 ] Affected animals are almost always adults and no sex predilection is apparent [ 9 , 11 , 12 , 13 , 14 ]. Most reports are cutaneous chromatophoromas that develop as single or multiple masses at various sites, including the head, trunk, limbs (when applicable), and tail [ 9 , 12 , 13 , 22 , 23 ].…”

“…Most reports are cutaneous chromatophoromas that develop as single or multiple masses at various sites, including the head, trunk, limbs (when applicable), and tail [ 9 , 12 , 13 , 22 , 23 ]. Chromatophoromas most often present as raised, pigmented masses, but more subtle alterations in scale pigmentation are less commonly described [ 9 , 12 , 13 , 14 ] ( Figure 1 a–e). Melanophoromas are often described as dark brown to black [ 8 , 9 , 12 , 13 , 24 ].…”

“…Xanthophoromas may be yellow, orange, or red [ 8 , 9 , 16 , 26 ]. Benign and malignant forms of each subset can occur, the latter sometimes with widespread metastases [ 8 , 9 , 11 , 12 , 13 , 14 ].…”

“…In most reptiles, exposure to adequate natural or artificial UV light is essential for the synthesis of vitamin D3 and calcium metabolism [ 30 , 31 ]. Therefore, given that many captive reptiles are exposed to artificial UV light daily, it has been speculated that UV radiation may contribute to the development of cutaneous chromatophoromas [ 8 , 14 ]. This theory is supported by the increased incidence of cutaneous chromatophoromas in sun-loving, day active reptiles, such as bearded dragons ( Pogona sp) and the paucity of tumors in nocturnal reptiles [ 8 , 9 , 13 ].…”

“…All chromatophores have the potential to undergo neoplastic transformation and are described collectively as chromatophoromas, or more specifically as melanophoromas (or melanomas), iridophoromas, and xanthophoromas [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Mixed or combination chromatophoromas involving multiple chromatophore varieties within the same tumor also occur [ 8 , 9 , 12 , 13 , 14 , 15 , 16 ].…”