Differential diagnosis between monomorphic clear cell adenocarcinoma of salivary glands and renal (clear) cell carcinoma.

Clear cell adenocarcinoma of salivary glands (CCASG) is a relatively rare tumor, composed entirely of clear cells of putative ductal origin. It bears striking morphologic similarities to renal cell carcinoma (RCC) of clear cell type on hematoxylin and eosin stains. Differentiation between CCASG and metastatic RCC to the salivary glands has been considered problematic or even impossible on morphologic grounds. We examined three cases of CCASG and 12 cases of RCC (6 primary and 6 metastatic) by hematoxylin and eosin staining, immunohistochemistry, and electron microscopy. Two distinctive immunohistochemical and ultrastructural patterns emerged from this analysis. CCASG showed positivity for high molecular weight cytokeratin and carcinoembryonic antigen and ultrastructurally showed prominent squamoid differentiation, glycogen pools, and absence of lipid. In contrast, RCC was characterized by positivity for vimentin and complete absence of staining for high molecular weight cytokeratin and carcinoembryonic antigen. On ultrastructural studies, RCC lacked any squamoid differentiation, and the tumor cells contained abundant cytoplasmic lipid in addition to glycogen. Thus, based on the consistent differences on the immunohistochemical staining patterns and their characteristic subcellular morphology, CCASG and RCC can be distinguished on pathologic evaluation. The different direction of differentiation of the cells in CCASG and RCC (i.e., ductal in the former and renal tubular and mesodermal in the latter) results in their distinctive immunophenotypical and ultrastructural features.

Artifact in cervical LLETZ specimens: correlation with follow-up.

The effect of cautery artifact on the ability to accurately diagnose dysplasia and predict abnormal follow-up in large loop excision specimens of the transformation zone (LLETZ) has not been adequately addressed in the pathology literature. One hundred consecutive conization specimens with cytologic and/or histologic follow-up were studied. Indications for the procedure were high-grade squamous intraepithelial lesion (on Pap smear and/or biopsy) in 64 cases, low-grade squamous intraepithelial lesion in 28, atypical squamous cells of unknown significance (ASCUS) in 3, atypical glandular cells of unknown significance in 2, adenocarcinoma in situ, squamous carcinoma in situ, and invasive squamous carcinoma in 1 each. Twenty-four specimens were cold-knife conizations (CKCs) and 76 LLETZs. All LLETZs had at least 1+ artifact, and in 46 cases (61%) it interfered with at least one aspect of evaluation. In 21 cases (28%), 1+ artifact interfered only with margin assessment. In 25 cases (33%), there was 2+ or 3+ artifact precluding not only margin assessment, but also diagnosis and grading of dysplasia. Of the 43 LLETZs received in more than one piece, 33 (77%) had interfering artifact, and in 21 (49%) it was 2+ or 3+, at least focally interfering with diagnosis and grading. In contrast, of 33 LLETZs received in a single piece, only 13 (39%) had interfering artifact, which was 2+ or 3+ in 4 (12%), (p < 0.05). Positive follow-up (including ASCUS, favor dysplasia, and ASCUS, not otherwise specified) was found in 6 of 7 CKCs with positive margins (86%), 10 of 16 LLETZs with positive margins (63%), and 4 of 7 LLETZs with unassessable margins (57%). In cases with negative cone margins, positive follow-up was found in 2 of 17 CKCs (12%), and 18 of 53 LLETZs (34%), p < 0.05; a higher frequency of interfering artifact (p < 0.05) was seen in these cases. LLETZ margin status and postprocedure endocervical curettage (ECC) specimens were not good predictors of residual disease, unlike margin status in CKC. Post-CKC ECC was a better predictor of subsequent abnormal follow-up than post-LLETZ ECC (p < 0.05). The presence of interfering artifact was only rarely mentioned in the original pathology report. In conclusion, the status of margins is a better predictor of abnormal follow-up in CKC than in LLETZ specimens. Fragmentation of the specimen is an additional factor, compounding the inevitable artifact. Postprocedure ECC is not a useful indicator of residual dysplasia. The pathologist should not hesitate to comment on specimen adequacy in surgical pathology reports.