Testis & paratestis

Sex cord stromal tumors

Fibroma thecoma group



Last author update: 9 May 2023
Last staff update: 9 May 2023

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PubMed Search: Fibroma thecoma group

Nadarra L. Stokes, M.D.
Rafael E. Jimenez, M.D., M.H.A.
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Cite this page: Stokes NL, Jimenez RE. Fibroma thecoma group. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testisfibroma.html. Accessed April 14th, 2024.
Definition / general
  • Sex cord stromal tumors composed of spindle, oval or round cells with varying amounts of collagen present
Essential features
  • Hemorrhage and necrosis absent
  • Variable cell density, variable collagen
  • Usually no Sertoli or granulosa elements present but may have minor aggregates of other sex cord cells (Arch Pathol Lab Med 1999;123:391)
  • Usually scanty mitoses (≤ 5 mitoses/10 high power fields), can be as high as 10 mitoses/10 high power fields
Terminology
  • Synonyms:
    • Fibrothecoma
    • Thecofibroma
    • Thecoma / fibroma group
    • Testicular fibroma
ICD coding
  • ICD-O:
  • ICD-10: D29.20 - benign neoplasm of unspecified testis
  • ICD-11: 2F34 & XH34A0 - benign neoplasm of skin of male genital organs & thecoma, NOS
Epidemiology
Sites
  • Testis
  • Paratestis
Pathophysiology
  • Unknown
  • May be associated with Gorlin syndrome (nevoid basal cell carcinoma syndrome), abnormalities of PTCH gene (J Pediatr Surg 2010;45:E1)
Etiology
  • Unknown
Clinical features
  • Commonly presents as slowly increasing unilateral testicular mass (Urol Ann 2021;13:308)
  • Hormonal changes are extremely uncommon
  • Clinically benign behavior with no reported recurrences or metastases (Urol Ann 2021;13:308)
Diagnosis
  • Ultrasound
  • Orchiectomy
Laboratory
  • Hormone levels are typically within normal range
  • Serum testosterone and estrogen may be elevated in some secreting tumors
  • Tumor markers (beta human chorionic gonadotropin [hCG], alpha fetoprotein [AFP], lactate dehydrogenase [LDH]) are within normal range (Urol Case Rep 2020;33:101368, Urol Ann 2021;13:308)
Radiology description
  • Well defined, hypoechoic, solid mass
  • Can appear as a heterogeneous mass
Prognostic factors
Case reports
Treatment
  • Diagnostic orchidectomy is curative; observation after orchidectomy is the only necessary treatment
Gross description
  • Well defined, firm tumors ranging from 0.5 to 7.6 cm in greatest dimension (Am J Surg Pathol 2013;37:1208)
  • Cut surface is tan, yellow or white and solid to cystic; can have focally hemorrhagic areas
Gross images

Images hosted on other servers:

Well circumscribed intratesticular tumor

Microscopic (histologic) description
  • 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
Microscopic (histologic) images

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

Bland nuclei

Fascicular pattern

Fascicular pattern

Encapsulated tumor

Encapsulated tumor

Collagenized stroma

Collagenized stroma

Inhibin

Inhibin

SF1

SF1

Negative stains
Electron microscopy description
  • Fibroma cells resemble both fibroblasts and myofibroblasts
Molecular / cytogenetics description
  • 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)
Sample pathology report
  • Right testis, orchiectomy:
    • Fibrothecoma (see comment)
    • Comment: The neoplastic cells showed positivity for inhibin, smooth muscle actin and SOX9 while MelanA, KIT and desmin were negative. This is consistent with the diagnosis above.
Differential diagnosis
  • 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
Board review style question #1

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
Board review style answer #1
B. Observation

Comment Here

Reference: Fibroma thecoma group
Board review style question #2
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
Board review style answer #2
C. Inhibin positive, FOXL2 positive, MelanA negative

Comment Here

Reference: Fibroma thecoma group
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