67 y/o M treated with colchicine for gout. Now with lower extremity weakness, normal CPK.

H&E

ATPase histochemistry, pH 4.3

ATPase histochemistry, pH 4.3

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Dx: Neurogenic atrophy (colchicine neuropathy with denervation changes)
Notes:
1) grouped atrophy in left figure, a sign of chronic denervation/reinnervation/denervation cycle
2) fiber type grouping in middle figure, also a sign of chronic denervation
3) target fibers in right figure, another sign of denervating disease