Bilateral thyroid follicular compact-cellular carcinoma in a llama

Abstract

An 18-y-old female llama ( Lama glama) in Saskatoon, Saskatchewan was examined during a routine herd check, and a mass was detected in the ventral cervical area just below the angle of the jaw. No clinical signs were evident except for the mass and chronic loss of body condition. Postmortem examination revealed bilateral enlargement of the thyroid gland with multiple cysts. Histopathology of the thyroid gland revealed follicular compact-cellular carcinoma lesions, with infiltration of neoplastic thyroid follicular cells in regional lymph nodes.

Bilateral thyroid adenomas in an alpaca

“…Veterinary literature indicates that 90% of thyroid tumors in dogs that are palpable on presentation are malignant 1 . However, it is uncertain if size can be used as a reliable indicator when determining malignancy in SAC because the benign adenomas in our case were of similar size to the previously reported malignant carcinoma in a llama 12 . The bilateral presentation in SAC is important information because it aids in narrowing the differential diagnosis list for lesions at the level of the cranial cervical region and helps dictate the treatment plan.…”

“…Laboratory testing performed in our alpaca indicated low serum T4 concentration when extrapolating from the RI in llamas, but because no validated RI is available for alpacas, these results potentially could be within the normal range. Serum thyroxine concentrations in the previously‐mentioned report of the 18‐year‐old llama with the carcinoma were within the RI 12 . This observation suggests that despite a lack of RI for alpacas, both malignant and benign lesions could be endocrinologically inactive in SAC, but further endocrinological investigation of thyroid neoplasia in SAC is required to support this hypothesis 4,12,15 .…”

“…The authors hypothesized that adenoma of the thyroid may progress to accumulation of colloid‐like material, forming larger cysts as the animal ages 11 . Advanced age also was noted in the aforementioned report of a cystic, bilateral, thyroid carcinoma in an 18‐year‐old llama 12 . This finding indicates that age potentially may be a risk factor for the development of thyroid lesions in SAC 11 .…”

“…However a retrospective study of necropsy findings in 77 llamas identified incidental benign thyroid adenomas and cysts in 29/77 animals 11 . In addition, a bilateral malignant thyroid carcinoma in a llama recently has been described 12 . Although almost half of the llamas in the retrospective necropsy study had evidence of thyroid lesions, this number equates to approximately 5% of the combined number of animals in the 3 aforementioned reports.…”

“… 11 In addition, a bilateral malignant thyroid carcinoma in a llama recently has been described. 12 Although almost half of the llamas in the retrospective necropsy study had evidence of thyroid lesions, this number equates to approximately 5% of the combined number of animals in the 3 aforementioned reports. This low incidence supports the rarity of the clinical condition, but thyroid lesions should not be ruled out as a differential diagnosis for cranial cervical mass lesions because evidence of their existence has been documented in SAC.…”