Lack of correlation between MSH3 immunohistochemistry and microsatellite analysis for the detection of elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) in colorectal cancers.

Immunohistochemical evaluation of mismatch repair protein (MMR) expression is an important screening tool in diagnostic pathology, where it is routinely used to identify subsets of colorectal cancers (CRCs) with either inherited or sporadic forms of microsatellite instability (MSI). MSH3 is not included in current MMR panels, although aberrant MSH3 expression is reported to occur in 40-60% of CRCs and is associated with elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) and a worse prognosis. In this study, we applied MSH3 immunohistochemistry and tetranucleotide MSI analysis to a cohort of 250 unselected CRCs to evaluate the potential use of the methods in routine practice. Partial, complete, and focal loss of nuclear MSH3 and its cytoplasmic mislocalization were evident in 67% of tumors, whereas MSI was evident in two to six of a panel of six tetranucleotide repeats in 46% of cases. However, concordance between MSH3 immunohistochemistry and tetranucleotide MSI results was only 61%, indicating the unsuitability of this combination of tests in routine pathology practice. MSH3 immunostaining was compromised in areas of tissue crush and autolysis, which are common in biopsy and surgical samples, potentially mitigating against its routine use. Although tetranucleotide MSI is clearly evident in a subset of CRCs, further development of validated sets of tetranucleotide repeats and either MSH3 or other immunohistochemical markers will be required to include EMAST testing in the routine evaluation of CRCs in clinical practice.

The importance of tubuloreticular inclusions in lupus nephritis.

Tubuloreticular inclusions (TRI) are distinctive cytoplasmic structures of unknown origin that typically associate with autoimmune and viral diseases. We investigated the clinical and prognostic relevance of TRI detection in patients with lupus nephritis (LN). We conducted a single centre study of patients (n=84) with biopsy evidence of LN. Clinical variables included demographics, SLEDAI score, and autoantibody profiling; while histological evaluation included TRI presence, International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification with NIH activity and chronicity indices, immunofluorescence, and other EM findings. Patients with and without TRI were compared by non-parametric statistical methods and survival analysis for the endpoints of death and renal failure. TRI were detected in 37 patients (44%) that were younger (28.4 vs 34.3 years, p=0.02) and more often from Asian background (37.8% vs 19.1%, p=0.04) compared to patients without TRI. SLEDAI score (11 vs 12 units, p=0.36) and amount of proteinuria (370 vs 340 mg/mmol, p=0.71) were similar in both groups; however, TRI positive patients had increased frequency of anti-SSB antibodies (16% vs 2%, p=0.02), 'full house' immune complex deposition (85% vs 58%, p=0.04) and subendothelial electron dense deposits (83% vs 65%, p=0.07), but were less often anti-dsDNA Ab positive (62% vs 85%, p=0.02). Patient and renal survival were not influenced by TRI status. TRI were observed in nearly half of all LN patients and TRI positive patients more often carried anti-SSB antibodies. However, TRI had little bearing on disease presentation or outcome in LN.

Laboratory validation studies in Ki-67 digital image analysis of breast carcinoma: a pathway to routine quality assurance.

Ki-67 proliferative index (PI) has prognostic and predictive value in invasive breast carcinoma (IBC), but clinical uptake has been hampered by suboptimal accuracy, reproducibility and standardisation. Published guidelines have addressed pre-analytical and analytical factors to improve Ki-67 PI utility; however, practicalities of ongoing monitoring of Ki-67 PI quality in IBC reporting have not been established. We aimed to evaluate the internal and external quality of our established digital Ki-67 PI IBC reporting practice at a tertiary institution. In the 5 years since initial validation work, we've completed a series of internal and external quality assurance (QA) projects: (1) an interobserver agreement study, (2) a two site interlaboratory agreement study, (3) determination of the error of our Ki-67 results, (4) an audit of the year-to-year Ki-67 values, (5) an audit of Ki-67 in neoadjuvant chemotherapy (NAC) treated cases, and (6) comparison of our Ki-67 datasets with similar published datasets. There was excellent concordance (intra-class correlation = 0.98) and good agreement [kappa (κ) = 0.76-0.96] between pathologists, excellent concordance [Pearson correlation (R) = 0.94] and very good agreement (κ = 0.80) between laboratories and excellent concordance (R = 0.92-0.95) and good agreement (κ = 0.67-1.0) over time for our Ki-67 results. No significant difference was observed in Ki-67 data from year-to-year. Expected associations with clinico-pathological prognosticators, pathological complete response following NAC and mitotic index were evident. The median Ki-67 values from the overall and NAC treated datasets were within the range reported in other studies, and our data could be separated into similarly proportioned 'high' and 'low' Ki-67 PI groups when dichotomised as per protocols in other studies. Collectively, our work provides evidence of adequate internal and external quality control for our digital Ki-67 PI IBC reporting protocols. Given the paucity of formal Ki-67 QA programs, our approach could be emulated, and results compared between laboratories as a framework for internal and external Ki-67 QA.

Manufactured Cell Blocks: Turning Smears into Sections.

Whilst cytological smears are still the basis of cytodiagnosis, there is an increasing role for ancillary testing. Specimens obtained are not always optimal, often with limited material for ancillary studies. Several reports have described the utility of scraping material from cytological smears to manufacture cell blocks to provide material for ancillary studies. Our objective was a retrospective review of the PathWest (QE2) experience with manufactured cell blocks (mCB) over the last 10 years. A total of 178 fine-needle aspiration cases with mCB were extracted from the PathWest database. Data were subdivided into: lymph node (89), breast (31), thyroid (23), soft tissue (13), liver (11), and other sites (11) and were analysed. All available material was reviewed. Diagnostic material was identified in 163 mCB (91.6%). Immunohistochemistry (IHC) was performed on 149 cases. Positive IHC staining was seen in 139 cases (93.3%) and advanced the diagnosis in 119 cases (79.9%). Molecular studies were performed on 38 mCB with adequate DNA obtained in 37 cases (97.3%). Our review has demonstrated that cellular material scraped from air-dried or prefixed smears can be made into cell blocks. Antigen preservation is adequate to provide diagnostically useful results with IHC whilst DNA integrity is preserved to allow molecular analysis.

A spontaneously resolving breast lesion: imaging and cytological findings of nodular fasciitis of the breast with FISH showing USP6 gene rearrangement.

We report a case of nodular fasciitis of the breast in a 48-year-old woman who presented with a tender rapidly growing right breast lump. Ultrasound guided fine needle aspiration (FNA) of the solid mass was performed. Cytology was reported as atypical spindle cell neoplasm and the patient was referred to a breast surgeon at a tertiary institution for a definitive diagnosis and further management. Follow-up ultrasound showed partial regression and MRI, mammogram after 2-3 weeks confirmed spontaneous and total resolution of the lesion. Nodular fasciitis of the breast is rarely diagnosed on cytology alone and a histological diagnosis is usually required for a definitive diagnosis. However, in this case, the lesion spontaneously resolved prior to core biopsy or diagnostic open biopsy. The cytological features in conjunction with immunohistochemistry and the clinical history strongly suggest nodular fasciitis, which is further supported by a USP6 FISH positive result.