Ovary tumor
Other ovarian specific tumors
Microcystic stromal tumor

Author: Eman Abdulfatah, M.D. (see Authors page)
Topic editors: Rouba Ali-Fehmi, M.D., Sudeshna Bandyopadhyay, M.D. and Dong Ping Shi, M.D.

Revised: 15 March 2016, last major update March 2016

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Microcystic stromal tumor [title] ovary
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)
Epidemiology
  • 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)
Diagnosis
  • Histologic recognition, confirmed by immunophenotype
Laboratory
  • No specific laboratory findings
Prognostic Factors
  • Benign behavior, no reports of recurrence or malignant transformation
Case Reports
Treatment
  • 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
Micro 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)
Micro 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