Presents as painless slowly enlarging testicular mass.
May elaborate androgen or estrogen but of low quantity to cause precocious musculinization or feminization.
May be seen in patients with Peutz-Jeghers syndrome, Carney syndrome, androgen insensitivity syndrome, and testicular feminization syndrome.
Gross: Usually well-circumscribed, homogenous, solid firm gray-white mass (image A).
Uniform cuboidal or columnar cells with moderate pale to lightly pink cytoplasm, often with prominent cytoplasmic lipid vacuoles (image B), (image C), & (image D).
Bland round to ovoid nuclei, occasional centrally located nucleoli, rare mitosis.
Growth patters: tubules (most common) and may resemble rete testis.
Other patterns include microcystic, cords, nests, solid sheets, and rarely spindled.
Hypocellular or hyalinized stroma.
May have abundant sclerosis (sclerosing SCT).
Charcot-Böttcher filaments (perinuclear arrays of filaments) pathognomonic electron microscopic feature.
Immunohistochemistry: Majority keratin+.
Mostly tumors have benign behavior; 10% are malignant.
Leydig cell tumor: cells have abundant pink cytoplasm and keratin-.
Seminoma with tubular pattern: has clear cells, fibrous septa and lymphocytic infiltrates; Oct3/4+ and inhibin-.