Case 60

A 54-year-old female presented with an ovarian mass.

1. What' the morphology impression of this tumor?

   A: Carcinoma

   B: Carcinosarcoma

   C: Sex-cord stromal tumor

   D: Granulosa cell tumor

   E: Embryonal carcinoma

   F: Sertoli-leydig cell tumor

   G: Poorly differentiated sertoli-leydig cell tumor

Answer

This is a case of moderately differentiated sertoli-leydig cell tumor with heterologous intestinal mucinous differentiation as the tubular structures can be seen in the last picture.

Subtype/Component	Morphologic Features	Leydig Cell Features	Additional/Unique Features	Immunohistochemical Profile
Well-Differentiated SLCT	- Sertoli cells arranged in open or closed tubules with minimal nuclear atypia and low mitotic activity.	- Present in clusters, cords, or singly within delicate fibrous stroma. - May be vacuolated, contain lipofuscin, and display Reinke crystals.	- Almost always occur as pure forms.	- Sertoli cells: Positive for vimentin, pancytokeratin, and sex cord markers (α-inhibin, calretinin, SF1, WT1, FOXL2). - Leydig cells: Typically show minimal FOXL2/WT1 staining but express α-inhibin and melan-A.
Moderately Differentiated SLCT	- Lobular pattern with Sertoli cells growing as nests, in hollow/solid tubules, or cords. - Exhibit mild to moderate (rarely bizarre) degenerative cytological atypia with modest mitotic activity.	- Present, often forming clusters at the periphery of lobules.	- May show admixture with heterologous elements (epithelial or, less commonly, mesenchymal). - Can be part of a spectrum with poorly differentiated areas.	- Immunoprofile similar to well-differentiated SLCT; however, retiform/poorly differentiated areas tend to lose expression of some sex cord markers.
Poorly Differentiated SLCT	- Composed predominantly of sarcomatoid stroma resembling primitive gonadal stroma. - Often includes a minor component of moderately differentiated SLCT. - Conspicuous mitotic figures.	- Typically sparse.	- Frequently associated with heterologous elements.	- More likely to show reduced staining for sex cord markers (α-inhibin, calretinin, SF1, WT1, FOXL2) compared to well-differentiated forms. - Leydig cells retain α-inhibin and melan-A expression when present.
Retiform SLCT	- Composed of anastomosing, slit-like spaces or papillae lined by cuboidal/columnar epithelium. - Alternatively, may display a multicystic, sieve-like pattern lined by flattened cells. - Can be focal within moderately/poorly differentiated SLCTs.	- Features not specifically highlighted; typically assessed in the context of overall SLCT immunoprofile.	- Represents a distinct architectural pattern that may be seen alone or as a component within other SLCT subtypes.	- Immunoprofile generally follows that of SLCTs, although retiform areas (and poorly differentiated regions) are more likely to be negative for sex cord markers.
Heterologous Elements	- Occur in approximately 20% of moderately and poorly differentiated SLCTs. - Most commonly consist of benign enteric mucinous epithelium; may also show borderline change or carcinoma. - Rarely, carcinoid tumours are seen. - Mesenchymal elements (e.g., cartilage or fetal-type skeletal muscle) may be present.	- Not applicable.	- Can be admixed with sex cord areas or present as discrete foci. - Epithelial elements display their native morphology; mesenchymal elements mimic cartilage or skeletal muscle.	- Exhibit the immunoprofile typical of their constituent tissues.

References: https://tumourclassification.iarc.who.int/chaptercontent/34/82

Case credit: https://qp.91360.com/9895.html?lang=en

Author: Wangpan Jackson Shi, MD