Testis & paratestis

Images hosted on other servers:

• Circumscribed but unencapsulated; encapsulated forms are rare
• Arranged in fascicles, storiform or a combination pattern in collagenized stroma with small blood vessels
• Herringbone pattern may be seen
• Variable cell density, variable collagen
• Usually scanty mitoses (≤ 5 mitoses/10 high power fields), can be as high as 10 mitoses/10 high power fields
• May be infiltrative and entrap seminiferous tubules; this feature has no impact on tumor behavior
• Usually no Sertoli or granulosa components are present but may have minor aggregates of other sex cord cells (Arch Pathol Lab Med 1999;123:391)
• If > 1 microscopic focus of other sex cord stromal cells, classify as mixed or unclassified since these tumors have metastatic potential unlike the classical fibroma

Contributed by Rafael E. Jimenez, M.D., M.H.A.

• Inhibin, SF1, smooth muscle actin, calretinin, SOX9, FOXL2, CD56, vimentin

• MIC2, CD34, KIT, keratin (occasionally positive), HMB45, MelanA, S100
• Desmin is typically negative but may be focally positive (Am J Surg Pathol 1997;21:296)

• Although loss of heterozygosity at 9q22.3 (PTCH locus) is observed in 40% of sporadic ovarian thecoma fibromas, only one case in testis has been reported (J Pediatr Surg 2010;45:E1)

• Fibrosarcoma:
  • Malignant tumor with infiltration, cytological atypia, frequent mitoses, necrosis
• Leiomyoma:
  • Positive for muscle markers; negative for inhibin and other sex cord stromal markers
• Neurofibroma:
  • Patchy S100 positive; negative for sex cord stromal markers
• Fibrous pseudotumors:
  • Less cellular, more inflammatory cells
• Solitary fibrous tumor:
  • CD34 positive; tends to arise from extratesticular tissues like tunica albuginea, tunica vaginalis, gubernaculum, not testicular stromal cells
• Unclassified sex cord stromal tumors:
  • Show more than focal incomplete Sertoli cell differentiation; strong positive S100 is useful stain
• Myoid gonadal stromal tumor:
  • Rare, usually well circumscribed tumor composed of densely packed spindle cells with variable intervening collagen deposits; the nuclei are tapered with inconspicuous nucleoli
  • Positive for SMA, S100, FOXL2 and SF1 and negative for SOX9
• Granulosa cell tumor:
  • Nodular growth pattern with cells showing nuclear grooves; luteinization of cells and mitotic figures are rare
  • FOXL2 mutations can be seen
  • Reticulin staining shows fibers surrounding aggregates of cells instead of individual cells as in fibrothecoma

• J Urol 2012;188:1944, Int J Gynecol Pathol 2019;38:143, Int J Gynecol Pathol 2018;37:305, eMedicine: Pathology of Sex Cord Stromal Testis Tumor [Accessed 13 December 2022]

A 65 year old man presented with a painless mass in his right testis. An ultrasound demonstrated a solid mass, measuring 5.4 cm in greatest dimension. He was scheduled for a radical orchiectomy. The resected tumor's histology is depicted in the image above. What is the best course of action after this diagnosis?

1. Chemotherapy
2. Observation
3. Orchiectomy
4. Radiation

B. Observation

Comment Here

Reference: Fibroma thecoma group

Which of the following immunohistochemical profiles best supports the diagnosis of a fibrothecoma of the testis?

1. Calretinin positive, S100 negative, CD34 positive
2. CD56 negative, inhibin negative, smooth muscle actin negative
3. Inhibin positive, FOXL2 positive, MelanA negative
4. MIC2 positive, FOXL2 negative, S100 negative

C. Inhibin positive, FOXL2 positive, MelanA negative

Comment Here

Reference: Fibroma thecoma group