The Cutaneous Histopathology of Thallium Poisoning

Thallium toxicosis in a Brittany Spaniel

“…These changes were consistent with histopathological findings previously reported in dogs with thallium toxicity. 7 Serum Tl concentrations confirmed the diagnosis (463 µg/L). The source of the poisoning remained unknown.…”

Effects of Thallium Ion on Cellular Components of the Skin

“…Although no pigmentation abnormalities are reported in thallium toxicity, this affinity nevertheless may potentiate the effect of thallium on hair. Third, thallium results in scaling and follicular plugging, suggesting that thallium alters the normal differentiation pattern of keratinocyte differentiation (7)(8)(9)(10)(11)(12)(13). The perifollicular pattern may be explained by concentration of thallium in follicular melanocytes (26).…”

“…Classic histopathologic changes have been observed in both patients with thallium toxicity and animals given large doses of thallium. These changes include follicular plugging, hypogranulosis, parakeratosis, and focal epidermal necrosis (6)(7)(8)(9)(10)(11). Changes in hair follicles are characterized by hair shaft frag-mentation, shift of hair follicles to catagen and telogen, and disruption of the internal root sheath.…”

“…Anagen hairs appear most susceptible to thallium alopecia, with dramatic effect seen in humans and rabbits, and less of an effect in mice and rats. Changes in the dermis consist of upper dermal edema, disruption of collagen, and dilation of superficial blood vessels (7). The epidermal changes suggest that thallium can alter the normal program of epidermal keratinization, and the shift of hair to catagen and telogen suggests that thallium affects cellular proliferation (7)(8)(9)(10)(11)(12)(13).…”

“…Changes in the dermis consist of upper dermal edema, disruption of collagen, and dilation of superficial blood vessels (7). The epidermal changes suggest that thallium can alter the normal program of epidermal keratinization, and the shift of hair to catagen and telogen suggests that thallium affects cellular proliferation (7)(8)(9)(10)(11)(12)(13). These findings suggest that thallium may exert effects on melanocytes, keratinocytes, and endothelial cells.…”