Cell block preparation by inverted filter sedimentation is useful in the differential diagnosis of atypical glandular cells of undetermined significance in ThinPrep specimens.

BACKGROUND

Atypical glandular cells of undetermined significance (AGUS) is not a well defined entity in the Bethesda system for reporting cervical cytology diagnoses. An AGUS diagnosis can reflect a variety of conditions ranging from the benign to the malignant. To help differentiate abnormalities associated with suspected AGUS in ThinPrep specimens, the authors devised a novel technique to prepare cell blocks that avoids disruption of glandular structures during preparation.

METHODS

In the authors' technique, the fluid remaining after the preparation of ThinPrep slide was subjected to sedimentation in the inverted ThinPrep filter cylinder that was used for slide preparation. Sediment that was formed after filtration was completed was collected by separating the filter from the bottom of the cylinder. Filter and sediment then were processed for histology cell block. Remarkable conservation of tissue architecture was noted with this technique, with results comparable to findings in endocervical curettage.

RESULTS

Seventy specimens with suspected AGUS were processed as described above, 57 of which contained interpretable tissue materials. Of these 57 specimens, 38 (67%) were found to be abnormal and 19 represented benign diagnoses. Final diagnoses in the abnormal AGUS group included 6 cases with AGUS that could not be classified further, 2 cases with invasive squamous cell carcinoma, 15 cases with high grade squamous intraepithelial lesions, 14 cases with adenocarcinoma (in situ or invasive) (including 3 with endometrial adenocarcinoma), and 1 case with endometrial hyperplasia.

CONCLUSIONS

Inverted filter sedimentation is a useful technique in the differential diagnosis of AGUS. It can provide a training tool with which to increase the sensitivity and specificity of AGUS diagnoses as well as occasionally provide immediate tissue confirmation.