Molecular Cancer Pathology Update

Genetic variant may eventually enable clinicians to differentiate between aggressive, indolent prostate tumors.
Medscape reported, "One of the biggest issues in prostate cancer is differentiating between men who have aggressive tumors that could be fatal and men who have indolent tumors that might never become clinically significant."

But, findings from a University of California-San Francisco study may ease some of that difficulty. The team identified a genetic variant, which "is located on the KIAA1217 gene," saying that "it shows a person's predisposition to aggressive prostate cancer." The hope is that it will, will enable clinicians to identify with more certainty men who are likely to have aggressive disease," which "could result in less overtreatment."

Updates on Molecular Cancer Pathology

1) Molecular profiling may help determine patient's response to cancer therapies, research suggests.
A pilot study of molecular profiling of tumors, helped to identify therapies that ultimately had an impact on the disease.The University of Texas MD Anderson Cancer Center and the Memorial Sloan-Kettering Cancer Center are "striving to profile individual tumors so that therapy can be personalized, which means that it has a better chance of working because it targets specific mutations found in that tumor. This also prevents patients from being exposed to drugs that have a limited chance of success, eliminating toxicity and improving quality of life.

2 )Scientists developing new techniques for detecting CTCs in cancer patients' blood-Medscape report
Measuring "circulating tumor cells (CTCs) in the blood of cancer patients" gives "an indication of whether or not the patient is responding" to treatment. Presently, "there is only one commercially available product to measure CTCs -- CellSearch (Veridex LLC)." Now, one device in development "promises to be cheaper and faster," say University of California-Los Angeles researchers. The "new technique is based on a microfilter device."

3) Bladder cancer cells may have two distinct genetic patterns, research suggests.
Bladder cancer cells have two distinct genetic patterns, depending on whether they are invasive or not," say University of Southern California-Los Angeles scientists. The "discovery opens the possibility of monitoring the disease by a simple urine test," which would enable clinicians to sidestep "invasive procedures."

4) Immune cells could be reprogrammed to attack prostate cancer, scientists say.
Reprogrammed immune cells could become targeted 'killing machines' against prostate cancer." In fact, "these reprogrammed T cells sharply reduced the levels of prostate specific antigen (PSA) in two patients with metastatic prostate cancer," scientists at the Roger Williams Medical Center said. But first, the team had to "isolate a patient's T cells from a blood sample and use genetic engineering techniques to make them sensitive to a molecule that only occurs in prostate cancer -- prostate specific membrane antigen, or PSMA."

5) Researchers say presence of certain variants in MC1R gene may increase melanoma risk.
Researchers from the University of Pennsylvania "analyzed 779 patients with melanoma and compared them to 325 healthy people." The investigators found that the "presence of certain variants in the MC1R gene was linked with at least a twofold increased risk of melanoma, and was largely confined to those people who would not normally be considered at increased risk."

False positive diagnosis in breast FNAC.

Some common lesion leading to false positive diagnosis in FNA of breast are listed with Keys to differentiate them.
Artifactual Atypia
Most common of these is disruption of cell aggregates by too vigorous smearing, which can mimic the loss of cohesion characteristic of malignant epithelial cells .
Excessive smearing pressure can also cause smudging of nuclei, giving a false impression of nuclear enlargement and pleomorphism.
Dying artifacts in alcohol-fixed Pap smears have a similar effect.

Hormonal Stimulation and Physiologic :Hyperplasia in Pregnancy and Lactation
Physiologic hyperplasia of acinar epithelial cells in late pregnancy and lactation can look worrying in FNA smears.
Key: The recognition of milky secretion is the main clue to a correct diagnosis to be correlated with clinical information.

Reactive Atypia
This is seen in mastitis fat necrosis, postoperative repair, and post radiation.
Key: Correct clinical information is important. A history of previous tissue injury and the presence of acute inflammatory cells (not just lymphocytes) rarely seen in breast cancer call for caution and careful evaluation of the nuclear structure of atypical cells.

Fibroadenoma
Epithelial atypia, most likely hormone related, can be prominent in smears of fibroadenoma. This is the most frequent cause of false positive diagnosis in breast FNA.
Key: In most cases, the atypical cells constitute only a minor part of the cell population. The presence of benign components is a safeguard against an erroneous malignant diagnosis.

Papillary Lesions
The combination of high cellularity, loss of cell cohesion, and variable nuclear atypia sometimes seen in smears from benign papillary lesions may raise a suspicion of malignancy. A false positive diagnosis is possible, particularly if a papillary microarchitecture is notidentified.
Key: In general, the presence of background apocrine cells, foam cells, and single bipolar nuclei suggest a benign papilloma.
REFERENCES
1. Franze´n S, Zajicek J. Aspiration biopsy in diagnosis of palpable lesions of the breast. Acta Radiol. 1968;7:241–262.
2. Zajdela A, Ghossein NA, Pilleron JP, et al. The value of aspiration cytology in the diagnosis of breast cancer: experience at the Foundation Curie. Cancer. 1975;35:499–506.
3. Greenberg M. Diagnostic pitfalls in the cytological interpretation of breast cancer. Pathology. 1996;28:113–121.

Reporting parameters for positive prostate needle biopsy

According to college of American pathologists (CAP)the mandatory items for reporting positive prostate biopsies are:

• Histologic type - typically adenocarcinoma (conventional/acinar, not otherwise specified)
• Histologic grade –primary (predominant) Gleason pattern + secondary (worst remaining) Gleason pattern
• Total Gleason score
• Tumour Quantitation - 3 possible methods for tumor qyuantification;
  1) % of prostatic tissue involved by tumour
  2 ) total linear mm of carcinoma
• 3) number of positive cores/total number of cores
  
• Periprostatic fat and seminal vesicle invasion should always be looked for and reported if identified, given their importance in developing an optimal treatment plan.

Optional parameters

• Reporting the presence or absence of perineural invasion and lymphatic/small vessel invasion is completely optional.


• Perineural invasion is of debatable prognostic significance and we likely continue to reported simply because we have always done so.


• Reporting the presence of high grade PIN in biopsies with adenocarcinoma is also completely optional.


• Interestingly, inflammation is listed as an optional item. It has been my experience that many clinicians will be interested in knowing about coexisting inflammation in positive biopsies (especially if it is appreciable in amount) as it may be of use in interpreting serum PSA at the time of the positive biopsy.
  

Importance of Immunohistochemistry in the Evaluation of follicular lymphoid lesion

Before discussing the utility of particular immunostains, it is important to review and understand some basics about the normal lymphoid follicle, in order to interpret the immunostains appropriately.
The difference between a primary follicle and a secondary follicle:
A primary or "resting" follicle: - a collection of B-cells in the cortex of the lymph node that has not been antigenically stimulated, and because of this, it does not have a germinal center.
A secondary follicle:- Once a primary follicle has been antigenically simulated, it acquires a germinal center, and at this point is referred to as secondary follicle.
Differential diagnosis of lymphoid lesion with follicular structures or nodules, :-
1) Resting (primary) follicles,
2) Secondary follicles (as a reflection of reactive follicular hyperplasia),
3) Follicular lymphoma,
4) Mantle cell lymphoma with a nodular growth pattern.
5) B cell SLL/CLL with prominent pseudofollicular proliferation centers.

Many times the distinction of non-neoplastic lymphoid follicles vs. neoplastic lymphoid follicles can be readily made on standard H&E morphology alone.
As we all know however, we see cases where this distinction is challenging, and in other situations we are faced with minuscule or suboptimal material.By understanding the expected phenotype of the lymphoid cells within each of the various types of lymphoid follicles, one can frequently render a confident diagnosis, even in the face of suboptimal material or a minimal biopsy sample.

The lymphocytes in primary (resting) follicle express B cell markers (such as CD20, CD79a, or Pax-5) and BCL2.CD23 may be positive or negative, but they lack BCL6,CD10, CD5, and cyclin D1, and they have a low Ki-67 proliferative fraction.
In contrast, in the germinal center of a secondary follicle, the lymphoid cells lack BCL2, CD5,CD23, and cyclin D1, express both BCL6 and CD10, and have a very high proliferative fraction, approaching 100%.
In follicular lymphoma, the neoplastic cells express B-cell markers, BCL2 and BCL6, and lack CD5, CD23 and cyclin D1, with a variable Ki-67 proliferative fraction. Most but not all follicular lymphomas express CD10, and some grade 3 follicular lymphoma lack BCL2.
In mantle cell lymphoma, the lymphocytes express B-cell markers, BCL2, CD5, and cyclin D1, typically lack BCL6 and CD23.
And finally, in B-cell small lymphocytic lymphoma/CLL, the neoplastic cells express B-cell markers,CD5, CD23, and BCL2, but lack BCL6, cyclin D1, and CD10.

Caveats for immuno interpretation:
Since some of these follicular or nodular structures to some extent consist of mixed B and T-cell populations, there are often minor populations of cells staining for the markers above that are listed as lacking, and for that reason in some cases it is easiest to interpret the immunostain results on low-power.
For example, in the case of primary (resting) follicles, there are often a small number of background cells that may express BCL6, CD10, and CD5. It is always a good idea to compare the extent of reactivity of the markers discussed with the extent of reactivity of the associated B cell markers. Finally, it must be kept in mind that CD23 stains a subset of the follicular dendritic cells (FDC) that may be present in these conditions, so care must be taken to not misinterpret CD23 reactivity of FDC as reactivity of the lymphocytes. Finally, it is worthwhile to note that some follicular lymphomas contain impressive numbers of non-neoplastic T-cells. Another point that must be made is this: "tumors do not read textbooks". As such, not all lymphoid proliferations will neatly fit into the expected patterns of reactivity discussed
above. For example, we have seen clear-cut cases of both follicular lymphoma and mantle cell lymphoma that have expressed strong CD23, a few mantle cell lymphomas that have expressed BCL6, and we have even seen a rare case of follicular lymphoma that expressed CD5.

Click on the images to enlarge them.

References:
1) CD10 and BCL-6 expression in paraffin sections of normal lymphoid tissue and B-cell lymphomas.Dogan A, Bagdi E, Munson P. Am J Surg Pathol. 2000 Jun;24(6):846-52.
2) Abnormal expression of bcl-10 protein in extranodal marginal zone B cell lymphoma of mucosa-associated lymphoid tissue lymphoma typeLi BZ, Zhou XY, Ye HT, Yang WT, Fan YZ, Lu HF, Shi DR. Zhonghua Bing Li Xue Za Zhi. 2007 Dec;36(12):819-24. Chinese.
3) Propath focus –Immunohistochemistry in the Evaluation of Follicular or Nodular Lymphoid Lesions, R. T. Miller, M.D