Table 2 Characteristics of reclassified and non-reclassified (i.e., SCST, NOS) cases.

Patient age: median (range)

42 years (16–59 years)

43.5 years (29–72 years)

43 years (2 months–69 years)

Cellularity

Moderate

Low to moderate

Moderate to high

Cytomorphology

All cases composed predominantly of spindle cells. A subset exhibits a minor component of epithelioid cells.

Variable, including cases with spindle cell components (“Sertoli-stromal”), abundant Leydig cells (not neoplastic), epithelioid cells, “histiocytoid” and stellate cells.

Variable; most commonly epithelioid or a combination of epithelioid and spindle cells.

Architecture

Fascicular and/or storiform. A subset demonstrates scattered foci of epithelioid cells arranged in trabeculae and/or cords/solid tubules.

Variable, including solid sheets, fascicles (in cases with a spindle cell component), solid nests, cords, and reticular/microcystic growth patterns. Areas with imperfect tubular (hollow or solid) and/or retiform architecture are focally present.

Variable. Most commonly solid sheets and nests. Other patterns include trabeculae, single cells and fascicles (in cases with a spindle cell component).

Size: median (range)

1.1 cm (0.9–3.5 cm)

1.1 cm (0.6–4.6 cm)

3.6 cm (0.7–9.8 cm)

Pleomorphism

Absent

Absent

Present in a subset (3 cases)

Lymphovascular invasion

Absent

Absent

Present in a subset (3 cases)

Mitoses: median (range)¹

3 (1–4)

<1 (0–11)

5 (1–169)

Necrosis

Absent

Absent

Present in a subset (3 cases)

IHC findings

Negative/noncontributory S100

Diffuse or multifocal nuclear beta catenin (>50% of the tumor cells)

Variable

Molecular findings

Absence of definite somatic pathogenic SNVs. Ploidy shifts with recurrent chromosome-level copy number gains.

CTNNB1 or APC mutations.

Variable nonrecurrent findings, including pathogenic APC, RB1 and TP53 variants. A subset chromosome-level copy number changes.