Sex cord stromal tumors

Microcystic stromal tumor

Last author update: 1 March 2016
Last staff update: 19 October 2020

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PubMed Search: Microcystic stromal tumor [title] ovary

Eman Abdulfatah, M.D.
Rouba Ali-Fehmi, M.D.
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Cite this page: Abdulfatah E, Ali-Fehmi R, Bandyopadhyay S, Shi DP. Microcystic stromal tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarytumormicrocysticstromal.html. Accessed September 25th, 2023.
Definition / general
Essential features
  • Features to establish a diagnosis of microcystic stromal tumor in well sampled specimens include:
    • A microcystic pattern and regions with lobulated cellular masses with intervening hyalinized, fibrous stroma
    • No morphologic features enabling any other specific diagnosis in the sex cord stromal category
    • No epithelial elements
    • No teratomatous or other germ cell elements (Am J Surg Pathol 2009;33:367)
  • Mean age of 45 years (range 26 - 63 years)
Pathophysiology / etiology
Clinical features
  • Patients present with symptoms attributable to a pelvic mass
  • Not associated with manifestations related to hormonal excess
  • Usually unilateral
  • Often < 5 - 10 cm (range 2 - 27 cm)
  • Histologic recognition, confirmed by immunophenotype
  • No specific laboratory findings
Prognostic factors
  • Benign behavior, no reports of recurrence or malignant transformation
Case reports
  • Excision results in complete cure
Gross description
  • Well demarcated, solid-cystic tumor, however either solid or cystic areas can predominate
  • Solid component has tan-white cut surface
  • Foci of hemorrhage or necrosis can be present
Microscopic (histologic) description
  • Distinctive triad of histologic features:
    • Microcysts: small round / oval cystic spaces that may coalesce to larger irregular channels
    • Solid cellular regions
    • Hyalinized fibrous stroma
    • Cells have moderate, finely granular eosinophilic cytoplasm, bland round/oval nuclei with fine chromatin and indistinct nucleoli
    • Foci of bizarre nuclei may be seen, low mitotic rate (up to 2/10HPF)
Microscopic (histologic) images

Images hosted on other servers:
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Well demarcated mass

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CD10, CD56, β-catenin, WT1, PR

Negative stains
Electron microscopy description
  • Tumor cells with predominantly spindle and stellate morphology with fewer epithelioid cells, arranged in a loose "microcystic" pattern
  • The cytoplasm shows intermediate filaments and variable amount of other organelles (Ultrastructural Pathol 2014;38:261)
  • The centrally placed nuclei are round with thin nuclear membranes and dispersed euchromatin
  • Some nuclei have prominent nucleoli
Molecular / cytogenetics description
Differential diagnosis
  • Adult granulosa cell tumor: oval cells with nuclear grooves, Call-Exner bodies, positive for inhibin and calretinin and FOXL2 gene mutation
  • Sertoli-Leydig tumor: positive for inhibin and calretinin
  • Steroid cell tumor: androgenic manifestations, positive for inhibin and calretinin
  • Thecoma: older women, estrogenic manifestations, positive for inhibin, calretinin and CD56
  • Yolk sac tumor: larger size, elevated serum AFP, Schiller-Duval bodies; positive for AFP immunostain
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