MICROINVASION IN LOW MALIGNANT POTENTIAL TUMORS OF THE OVARY

The presence of microinvasion (Mi) has not previously been investigate d in nonserous low malignant potential (LMP) tumors of the ovary. In s erous LMP tumors (SLMP), Mi has not worsened the prognosis compared wi th usual SLMP in previous reports. In a retrospective clinicopathologi c review of 126 cases of serous and mucinous LMP (MLMP) tumors of the ovary, the authors identified 14 cases with Mi: seven of 72 SLMP, four of 44 mucinous intestinal LMP (MILMP), and three of 10 mucinous mulle rian LMP (MMLMP). Tumors with Mi resembled usual LMP histologically ex cept for small foci (up to 0.2 cm) in the stroma consisting predominan tly of single cells or small clusters of cells, sometimes in a cribrif orm pattern. In SLMP-Mi, the cells had eosinophilic cytoplasm, and the stromal reaction was minimal/absent. In MILMP-Mi and MMLMP-Mi, nuclea r staining was paler; the stroma often showed a fibrous reaction or ed ema, especially in MILMP-Mi. All 14 patients had follow-up (2.2 to 18. 6 years) and were without evidence of disease. Careful screening of bo th mucinous and serous ovarian LMP can show Mi. Mi foci should be dist inguished from true stromal invasion, pseudoinvasion, endothelial cell s, decidual cells and histiocytes, and pseudomyxoma in mucinous LMP. M i does not seem to worsen prognosis in MLMP and SLMP tumors of the ova ry. Copyright (C) 1996 by W.B. Saunders Company