Adenomatoid Tumor

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Definition

Benign tumors of mesothelial origin involving serosal surfaces of uterus and fallopian tube.

Pathogenesis

Mesothelial nature:
- established by ultrastructural and immunohistochemical findings1–4
- supported by occasional coexistence with other lesions of reputed mesothelial derivation, such as benign multicystic mesothelioma 5

Gross Pathology

In uterine wall:
- usually beneath serosa and close to cornua (Fig. 1
  Fig. 1: Adenomatoid tumor of uterus. Gross appearance. The location at one of the cornua is characteristic.
  )6,7
Exceptionally apparent in a curetting specimen
Usually small:
- mean diameter 2 cm

Histopathology

Adenoid, angiomatoid, solid, and cystic patterns:
- singly or in combination 8,9 (Fig. 2
  Fig. 2: Adenomatoid tumor of uterus. Microscopic appearance showing tubular formations lined by flattened mesothelial cells.
  )
Often smooth muscle hypertrophy
Ultrastructurally:
- mesothelial nature1–4

Special Stains and Immunohistochemistry

Immunohistochemically:
- mesothelial nature 1–4

Differential Diagnosis

Select up to 2 differential diagnoses to compare with Adenomatoid Tumor

Identical to those more commonly seen in fallopian tube
Cystic examples can simulate lymphangioma
If smooth muscle hypertrophy can be confused with leiomyoma

References

1 Otis CN. Uterine adenomatoid tumors: immunohistochemical characteristics with emphasis on Ber-EP4 immunoreactivity and distinction from adenocarcinoma. Int J Gynecol Pathol. 1996;15:146–151.

2 Shintaku M, Sasaki M, Honda T. Thrombomodulin immunoreactivity in adenomatoid tumour of the uterus. Histopathology. 1997;28:375–377.

3 Stephenson TJ, Mill PM. Adenomatoid tumours. An immunohistochemical and ultrastructural appraisal of their histogenesis. J Pathol. 1986;148:327–335.

4 Suzuki T, Yoshida Y, Kaku T, Kikuchi K, Mori M. Adenomatoid tumor of the uterus. Ultrastructural, histochemical, and immunohistochemical analysis. Arch Pathol Lab Med. 1985;109:1049–1051.

5 Chan JKC, Fong MH. Composite multicystic mesothelioma and adenomatoid tumour of the uterus: different morphological manifestations of the same process?. Histopathology. 1997;29:375–377.

6 Nogales FF, Isaac A, Hardisson D, Bosincu L, Palacios J, Ordi J, et al. Adenomatoid tumors of the uterus: an analysis of 60 cases. Int J Gynecol Pathol. 2002;21:34–40.

7 Tiltman AJ. Adenomatoid tumours of the uterus. Histopathology. 1980;4:437–443.

8 Palacios J, Suarez Manrique A, Ruiz Villaespesa A, Burgos Lizaldez E, Gamallo Amat C. Cystic adenomatoid tumor of the uterus. Int J Gynecol Pathol. 1991;10:296–301.

9 Quigley JC, Hart WR. Adenomatoid tumors of the uterus. Am J Clin Pathol. 1981;76:627–635.

Last updated: 24 Mar 2006