Page 758 - Textbook of Pathology, 6th Edition

742 I. TUMOURS OF SURFACE EPITHELIUM much better prognosis than frankly malignant tumours of
(COMMON EPITHELIAL TUMOURS) the ovary.
Based on this categorisation of biologic behaviour, groups
Tumours derived from the surface (coelomic) epithelium of surface epithelial ovarian tumours are described below:
called common epithelial tumours form the largest group of
ovarian tumours. This group constitutes about 60-70% of all Serous Tumours
ovarian neoplasms and 90% of malignant ovarian tumours. Serous tumours comprise the largest group constituting
The common epithelial tumours are of 3 major types—serous, about 20% of all ovarian tumours and 40% of malignant
mucinous and endometrioid, though mixtures of these epithelia
may occur in the same tumour. These tumours frequently ovarian tumours. They are called serous tumours because of
the presence of clear, watery, serous fluid in these
have prominent cystic component which may have a single predominantly cystic tumours. About 60% of serous tumours
or multiple loculations and hence the descriptive prefix are benign, 15% borderline and 25% malignant. Only 20% of
cystadeno- in these tumours. In addition, surface epithelial
benign tumours occur bilaterally, whereas 65% of both
tumours may differentiate along urothelium to form Brenner borderline and malignant serous tumours have bilateral
tumour, and along mesonephroid pattern forming clear cell ovarian involvement. Serous tumours occur most commonly
(mesonephroid) adenocarcinoma. in 2nd to 5th decades of life, the malignant forms being more
Depending upon the aggressiveness, the surface epithe- frequent in later life.
lial tumours are divided into 3 groups: clearly benign, clearly Histogenesis of the serous tumours is by metaplasia from
malignant, and borderline (or atypical proliferating or low-grade) the surface (coelomic) epithelium or mesothelium which
malignant tumours. In general, the criteria for diagnosis of differentiates along tubal-type of epithelium.
these 3 grades of aggressiveness are as follows (Fig. 24.20):
Clearly benign tumours are lined by a single layer of MORPHOLOGIC FEATURES. Grossly, benign,
well-oriented columnar epithelium. Papillary projections, if borderline and malignant serous tumours are large (above
present, are covered by the same type of epithelium without 5 cm in diameter) and spherical masses. Small masses are
any invasion into fibrovascular stromal stalk. generally unilocular while the larger serous cysts are
multiloculated similar to the mucinous variety, but differ
Clearly malignant tumours have anaplastic epithelial from the latter in containing serous fluid rather than the
component, multilayering, loss of basal polarity and viscid fluid of mucinous tumours. Malignant serous
unquestionable stromal invasion. The prognosis of these tumours may have solid areas in the cystic mass. Exophytic
SECTION III
tumours is very poor.
as well as intracystic papillary projections may be present
Borderline (atypical proliferating) tumours or tumours in all grades of serous tumours but are more frequent in
with low malignant potential have some morphological malignant tumours termed papillary serous cystadeno-
features of malignancy, apparent detachment of cellular carcinomas (Fig. 24.21).
clusters from their site of origin and essential absence of Histologically, the features are as follows:
stromal invasion. Morphological features of malignancy 1. Serous cystadenoma is characteristically lined by
which may be present in varying combinations include: strati- properly-oriented low columnar epithelium which is
fication (2-3 layers) of the epithelial cells but generally sometimes ciliated and resembles tubal epithelium.
maintained basal polarity of nuclei, moderate nuclear Microscopic papillae may be found.
abnormalities, and some mitotic activity. This group has a
Systemic Pathology

Figure 24.20 Diagrammatic representation of general histologic criteria to distinguish benign, borderline (atypical proliferating) and malignant
surface epithelial tumours of the ovary.