1 Department of Pathology and 2 Department of Obstetrics and Gynecology, Instituto Universitario Dexeus, Paseo de la Bonanova 69, 08017 Barcelona, Spain
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Abstract |
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Key words: endometrial ablation/histology/hysterectomy/morphological changes/uterus
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Introduction |
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Materials and methods |
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Ultrasonographic studies were performed in eight of these 12 patients before endometrial ablation and in six before hysterectomy. The mean time elapsed between ultrasonography and ablation was 4 ± 3.8 months (range 112 months) and between ultrasonography and hysterectomy 0.8 ± 0.7 months (0.12 months). The ultrasonographic studies were performed with a Toshiba SSA 270 A ultrasonograph (Toshiba Co., Tokyo, Japan) using a 6 mHz real time vaginal probe at a 150° angle. The endometrial thickness was determined measuring the larger distance between both endometriummyometrium interfaces in longitudinal sections.
Clinical data were focused on hormonal therapy, previous pregnancy, the cause of endometrial ablation and the indication for hysterectomy in each patient.
In ablation specimens the variables recorded were weight, size and the greatest endometrial thickness (measured from the surface epithelium to the endometrialmyometrium junction of perpendicularly oriented specimens in areas without pathological changes). The number of histological slides examined for each case ranged from three to six.
Endometrial thickness in hysterectomy specimens was also measured, and all the specimens were microscopically examined for tissue destruction and pathological associated disorders. The number of endometrial representative histological slides reviewed ranged from one to three.
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Results |
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The mean endometrial thickness in the seven cases in which the endometrium was present was 1.7 ± 1.2 mm (range 0.54) (Table II). Ultrasonography did not reveal an endometrial line in the four cases in which no endometrial lining was seen at hysterectomy. Coagulative necrosis was seen in three cases, in which the endometrium and superficial myometrium showed only ghost remnants with variable amounts of inflammatory cells. In these cases numerous coagulated and thrombosed small vessels with fibrinoid necrosis of their walls were also seen. Fibrosis with hyalinosis and scar formation was observed in four cases. In one of these cases (no. 1) electrosurgical myometrial damage such as nuclear streaming, hyperchromasia and cytoplasmatic eosinophilia were seen. Four specimens showed granulomatous reaction, consisting of a central core of amorphous, eosinophilic necrotic material surrounded by a rim of palisade histiocytes (Figure 3
). In these cases, multinucleated foreign body giant cells were also seen, most of them containing golden-brown intracytoplasmatic pigment. This pigment was also seen in the centre of granulomas and mixed with necrotic material in the inner uterine surface. In two of the four cases with granulomatous reaction, a prominent inflammatory eosinophilic cell infiltrate was detected and in another case the eosinophilic response was diffusely seen throughout the endometrium. In three specimens, scattered macrophages containing golden-brown intracytoplasmic pigment were seen located deep in the myometrium (Figure 4
). These cells were not accompanied by granulomatous reaction and no inflammatory response could be elicited.
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Six of the seven patients with endometrial regeneration had adenomyosis in the hysterectomy specimen and four of them also had this finding in the ablated specimens. Among those five patients without endometrial regeneration, only two had adenomyosis in the ablation and only one showed this alteration at hysterectomy. Only one case without endometrial regeneration showed adenomyosis at hysterectomy. The case with electrosurgical burn changes (no. 1) was the only case with an elapsed time of <1 month. In cases with endometrial re-growth, the endometrium was thinner in hysterectomy specimens than ablation tissue in two cases, in contrast to a thicker mucosa in the five remaining cases.
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Discussion |
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In gross specimens, stenosis and adhesions are the most common features (Davis et al., 1998) resulting in irregularities and distortion of the uterine cavity that can be a hindering factor for post-ablation pregnancies. It has also been speculated that these, along with retained endometrial islets, can subsequently undergo malignant degeneration (Horowitz et al., 1995
).
In-vitro studies in fresh hysterectomies have demonstrated that using a mean power resectoscope of 50100 W, almost all endometrial glands are destroyed, the degree of destruction being related to the mean power used. However a small portion of endometrial glands survive beneath the zone of destruction regardless of the power setting. This fact could explain the recurrence of abnormal uterine bleeding after ablation occurring in some patients and the presence of regrowing endometrium in post-ablation specimens (Letterie et al., 1993). In our series, seven of 12 post-ablation hysterectomies showed endometrial regeneration, the elapsed time between ablation and hysterectomy in these patients being larger than in patients without regeneration of the endometrium. The finding of adenomyosis in six of these seven patients favours the hypothesis of endometrial regeneration from endometrial islands located deep in the myometrium, but not destroyed by ablation as has been previously suggested (Davis et al., 1998
). Other studies have demonstrated that angiogenesis can play an important role in endometrial regeneration (Kooy et al., 1996
) because in histologically normal post-ablation endometrium there is an increase in endothelial cell number but a low endothelial cell proliferation, suggesting a low turn-over of endothelial cells in these specimens.
Necrotizing granulomas similar to those seen in rheumatoid arthritis are one of that most frequent microscopical findings in post-ablation specimens (Ashworth et al., 1991; Thurrell et al., 1991
; Ferryman et al., 1992
; Davis et al., 1998
). They consist of a central core of necrosis with a rim of palisade histiocytes and a multinucleated foreign body giant cell reaction. Sometimes within the giant cells and in the necrotic centre, a golden-brown material can be seen (Clarke and Simpson, 1990
; Ashworth et al., 1991
; Thurrell et al., 1991
). Electron diffraction analysis of this material has proved it contains carbon and aluminium oxalate (Thurrell et al., 1991
). The origin of these granulomas in post-TURP specimens has been attributed to an altered collagen reaction as a result of previous surgery or to the metal deposition from the instruments used (Henry et al., 1993
). Eosinophilic reaction in these granulomas should not be attributed to allergy. Its presence is more evident in those cases with a short-interoperative period (Lee and Shepherd, 1983
). We have not been able to find previous reports dealing with the presence of deeply located pigment-containing macrophages in the myometrium. The pigment, most likely carbon particles due to thermal effects during the ablation, has similar optical characteristics to that found in the granulomas and in the inner surface of the uterine wall.
Endometrial regeneration, scarring and fibrosis seem to be long-term post-ablation findings. Necrosis, granulomatous and foreign-body giant cell reaction, eosinophilic infiltrate and pigment containing macrophages in the myometrium are histological features found in post-ablation hysterectomies with a short intersurgical period. All these findings in post-ablation hysterectomies should not be confused with lesions due to other agents, allergic or infectious (Ashworth et al., 1991).
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Notes |
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References |
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Submitted on November 23, 1998; accepted on February 17, 1999.