Case 56 - Discussion

Uploaded: 2007-06-06, Updated: 2007-10-29
   
 

COMMENT:

The immunohistochemistry profile supports the diagnosis of adenomatoid tumor (CK AE1/3 and EMA positive, CEA negative, and CD34 highlights the vascular structures of the tumor). The tumor is a benign extra-testicular neoplasm of low incidence.
   
 

Adenomatoid Tumor

The Key Features

  • Confined to genital tract (male-epididymis, female-uterus and fallopian tube);

  • Benign mesothelial tumor;

  • Flattened or cuboidal epithelioid cells arranged in irregular, dilated vascular-like, tubular channels, gland-like, or strands/cords patterns;

  • Frequently lymphoid aggregates and may contain abundant smooth muscle fibers;

  • Calretinin and cytokeratin positive.

CLINICAL FEATURES
 

  • Benign mesothelial tumor usually confined to the genital tract of both genders; usually an incidental finding;

  • In male, most commonly in epididymis and also the most common tumor in epididymis, also in spermatic cord, testicular tunic, prostate, ejaculatory duct and testes; In female, most commonly in uterus and fallopian tubes, also in ovary;

  • Peak age, 30-60 years;

  • Usually solitary small indurate painless mass.

GROSS FINDINGS
 

  • Small firm well-circumscribed mass, usually <2.0 cm;

  • Smooth, glistening, yellow-gray cut surface.

MICROSCOPIC FINDINGS
 

  • Variable patterns, the epithelioid cells may be arranged in irregular, dilated tubular channels, gland-like,  vascular-like, strands/cords or solid patterns;

  • Lined by flattened or cuboidal cells with abundant eosinophilic cytoplasm;

  • Frequently lymphoid aggregates;

  • May contain abundant smooth muscle fibers and elastic fibers.

DIFFERENTIAL DIAGNOSES
 

  • Epithelioid hemangioma: CD31, CD34 and factor VIII positive; cytokeratin negative.

IMMUNOHISTOCHEMISTRY AND SPECIAL STAINS
 

  • Calretinin, EMA and Cytokeratin positive;

  • Factor VIII, CEA and CD31 negative.

ELECTRON MICROSCOPIC FINDINGS
 

  • Long, bushy microvilli on the luminal surfaces and the intercellular surfaces.

TREATMENT AND PROGNOSIS
 

  • Benign lesion.

REFERENCES
 

  • Enzinger and Weiss's Soft Tissue Tumors, 4th Edition. By Drs. Sharon Weiss and John Goldblum;

  • Rosai and Ackerman's Surgical Pathology, 9th edition