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2012, Volume 28, Number 1, Page(s) 017-023
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DOI: 10.5146/tjpath.2012.01092
Grade of Atypia in Dysplastic Nevi and Relationship with Dermal Fibroplasia
Ahmet BABACAN , Banu LEBE
Department of Pathology, Dokuz Eylül University, Faculty of Medicine, İZMİR, TURKEY
Keywords: Dysplastic nevus, Atypia, Dermal fibroplasia
Abstract
Objective: Dysplastic nevus is described as an important factor in increasing the risk of melanoma. Many authors suggested dysplastic nevi should be graded according to architectural and cytological features. Dermal fibroplasia can be in concentric or lamellar fashion. In our study we aim to grade architectural and cytological atypia in dysplastic nevi and to assess the relationship between atypia and dermal fibroplasia.

Material and Method: Ninety-three biopsies obtained from 71 patients were included in the study group. Hematoxylin-eosin stained slides were evaluated and graded according to architectural and cytological features. A total score was obtained for both architectural and cytological atypia in each case. Masson Trichrome stained sections were used to assess dermal fibroplasia and evaluated semiquantitatively.

Results: Twenty-eight (30.1%) cases had mild, 48 (51.6%) cases moderate, and 17 (18.3%) cases had severe atypia regarding architectural features. Nine (9.7%) cases were scored having mild, 28 (30.1%) cases moderate, and 56 (60.2%) cases having severe atypia regarding cytologic features. There was a significant correlation between the degree of architectural and cytologic atypia. Six (21.4%) cases with mild, 31 (64.6%) cases with moderate,, and 12 cases (70.6%) with severe architectural atypia had dermal fibroplasia. One case (11.1%) with mild, 10 cases (% 35.7) with moderate, and 10 cases (67.9%) with severe cytological atypia had dermal fibroplasia. A significant relationship was found between the presence of fibroplasia and the degree of cytological and architectural atypia.

Conclusion: A statistically significant relationship was revealed between the increase of architectural and cytological atypia and dermal fibroplasia. Detection and evaluation of stromal changes by histochemical methods, and scoring of atypia in dysplastic nevi may be helpful to distinguish dysplastic from other banal nevi.

Introduction
Ever since the histological definition of dysplastic nevus (DN) by Clark et al., discussions have focused on the relationship between the histological changes and malignant melanoma (MM) risk and familial MM1. Familial DN syndrome is the presence of multiple nevi together with a familial or personal MM history. Sporadic DN syndrome is the presence of a varying number of nevi without any familial history2,3. The melanocytic nevi seen with DN syndrome histologically show melanocytic dysplasia and their microscopic appearance is said to be associated with a markedly increased neoplastic risk2. Clark et al. have considered architectural and cytological atypia together in the diagnosis of melanocytic dysplasia4. Major and minor criteria have been defined for DN diagnosis. Papillary dermal fibroplasia, one of the minor criteria, is in the form concentric eosinophilic fibroplasia or lamellar fibroplasia5,6.

Many recent epidemiological1,7,8, morphological1,7-10, immunohistochemical11-14 and genetic15-20 studies support the notion that DN is a major risk factor for melanoma even if not a direct precursor.

Many studies support atypia grading for DN but there is marked variability both for intra-observer and interobserver values21-24. Neoplastic stromal changes progress together with the characteristic parenchymal changes in melanocytic tumor progression6. A band-like lymphocytic infiltrate together with diffuse fibroplasia is seen more commonly in MM25. There are many opinions on the development mechanism for the dermal fibroplasia during the MM tumorigenesis6,25 but there is no study on the relationship between architectural and cytological atypia grading in DN's and dermal fibroplasia. The aim of this study was to evaluate atypia according to architectural and cytological features of DN and to demonstrate the potential relationship of this atypia with dermal fibroplasia.

  • Top
  • Abstract
  • Introduction
  • Methods
  • Results
  • Disscussion
  • References
  • Methods
    A total of 93 lesions from 71 patients diagnosed as DN between the years 2003 and 2008 at Dokuz Eylul University Department of Pathology were included in this study. The patient's personal history, age, gender, and the anatomical localization of the lesion were found from the files and recorded. The 4 μm thick Hematoxylin & Eosin (H&E) stained sections that had been prepared from formalinfixed and paraffin embedded tissues were re-evaluated by two pathologists (AB and BL) and DN diagnoses were confirmed. The atypia of the cases included in the study were scored and graded according to Shea et al.26. Table I summarizes the architectural and cytological atypia.


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    Table I: Architectural and cytological atypia grading criteria

    The architectural features, circumscription, symmetry, cohesion, suprabasal melanocytes, confluence, and single cell proliferation were scored and evaluated. The total of obtained scores gave the degree of architectural atypia. 0-1= Mild architectural atypia (MiAA), 2-3 = Moderate architectural atypia (MoAA), 4-6 = Severe architectural atypia (SAA). The cytological features were evaluated by scoring the nuclear shape and staining, nuclear size, nucleolar prominence and melanocyte cell size.

    The total of obtained scores gave the degree of cytological atypia as 0-1: Mild cytological atypia (MiCA), 2: Moderate cytological atypia (MoCA) 3-4: Severe cytological atypia (SCA). Masson's Trichrome histochemical technique was used to show dermal fibroplasia in DN27. The sections stained with Masson's Trichrome stain were evaluated under light microscopy by 2 pathologists and were scored semiquantitatively as fibroplasia present (1) or absent (0).

    The architectural and cytological grades and histochemical staining characteristics of the cases were evaluated with statistical analysis. The association between the degree of atypia in the DN and the Masson Trichrome staining scores was investigated. Data were analyzed using Scientific Package for Social Sciences Software (SPSS) and Epi Info 2002 Statcalc programs. Pearson Chi square, Chi square test for trend and Spearman correlation tests were used. A p value less than 0.05 was accepted as significant.

  • Top
  • Abstract
  • Introduction
  • Methods
  • Results
  • Disscussion
  • References
  • Results
    The age range of the 71 cases included in the study at the time of diagnosis were 12 to 75 years with median value of 33.62. The cases were distributed as 32 females and 39 males. There were 93 DN lesions from 71 patients. The DN lesions were distributed as 33 (35.5%) junctional and 60 (64.5%) compound lesions.

    Table II shows the distribution of the cases by anatomic localization.


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    Table II: Distribution of the cases by anatomical localization

    The most common architectural disorders were confluence in the junctional melanocytes (Figure 1), the loss of termination with a nest in one or both ends and the presence of single cell melanocytic proliferation.


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    Figure 1: Confluence of the junctional melanocytes in dysplastic nevus (Hematoxylin eosin, x200).

    The architectural atypia features of the cases have been summarized in Table III. We found MiAA in 28 cases (30.1%), MoAA in 48 cases (51.6%) and SAA in 17 cases (18.3%).


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    Table III: Architectural atypia features and scores of the cases

    The most common cytological features were abnormal nuclear shape and staining pattern (Figure 2), large cell diameter, nucleolar prominence and marked nuclear enlargement. Table IV summarizes the cytological atypia features and scores. We found MiCA in 9 cases (9.7%), MoCA in 28 cases (30.1%) and SCA in 56 cases (60.2%).


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    Figure 2: Abnormal nuclear shape and nuclear pattern in the melanocytic cell in dysplastic nevus (Hematoxylin eosin, x400).


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    Table IV: Cytological atypia features and scores of the cases

    A total of 6 MiAA cases (21.4%), 31 MoAA cases (64.6%), and 12 SSA cases (70.6%) showed marked dermal fibroplasia with Masson Trichrome histochemistry (Figure 3) (Table V).


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    Figure 3: Dermal fibroplasia in a dysplastic nevus with severe architectural atypia (Masson's Trichrome stain, x200).


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    Table V: Association between the degree of architectural atypia and dermal fibroplasia

    Marked dermal fibroplasia on Masson Trichrome histochemistry was also found in 1 MiCA case (11.1%), 10 MoCA cases (35.7%) and 10 SCA cases (67.9%) (Figure 4) (Table VI).


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    Figure 4: Dermal fibroplasia in a dysplastic nevus with severe cytological atypia (Masson's Trichrome stain, x100).


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    Table VI: Association between the cytological atypia grades and dermal fibroplasia

    The presence of dermal fibroplasia changed with the degree of architectural atypia (p<0.001, r= 0.354). The increased incidence of fibrosis with increasing architectural atypia degree (χ2= 15.88, p<0.0001) was found to be statistically significant.

    The presence of dermal fibroplasia changes with the degree of cytological atypia (p<0.001, r= 0.371). We found the increasing incidence of fibrosis with increasing degree of cytological atypia to be statistically significant (χ2= 14.64, p<0.001).

    The degree of architectural atypia changed with the degree of cytological atypia (p=0.05).

    The presence of single cell proliferation that is the architectural atypia grading parameter changed with the presence of hyperchromatic or irregular shape nuclei that are features of cytologic atypia (p=0.013, r=0.233). Similarly, the termination of the junctional component with a nest at both ends, that is a parameter of architectural atypia, changed significantly with the presence of a hyperchromatic or irregular shaped nuclei, that are cytological atypia parameters (p=0.005, r=0.154).

    Nucleolar prominence changed with discohesion of nests (p=0.013, r=0.202) and single cell proliferation (p=0.000, r=-0.449).

    A cell diameter over twice the basal keratinocyte nucleus diameter changed significantly with more than 50% bridge formation between junctional melanocytic nests or the presence of continuous single melanocytic cellular proliferation (p=0.011, r=0.230).

    We also found a significant relationship between nucleolar prominence and the lack of termination of the junctional component with a nest at both ends (p=0.008, r=0.153).

  • Top
  • Abstract
  • Introduction
  • Methods
  • Results
  • Disscussion
  • References
  • Discussion
    DN is an important risk factor and potential precursor for MM. Clark et al. were the first to show transformation to MM in two cases with a family history of MM and they named this condition the “B-K mole syndrome”1. The lifelong risk of MM development in cases with the familial DN syndrome is almost 100% while this risk is 2 to 8 times higher than the general population in the sporadic DN syndrome5. Many investigators recommend grading melanocytic atypia but the study results show a high degree of variability21-26,28-32. As far as we know, there is also no study on the possible relationship between these atypia degree and fibroplasia in the English literature.

    Pozo et al.24 have graded DN cases as low, moderate or high degree of dysplasia. We found severe dysplasia in 99.5% of DN cases using this criteria. However, we were unable to define significant architectural features that differentiated between a low and moderate degree of dysplasia. All the cases in the series had both architectural and cytological atypia. This study did not find a significant relationship between the nuclear pleomorphism and chromatin pattern and the severe atypia degree, in contrast to our findings. We separately scored the architectural and cytological features in DN cases and graded the atypia. We also evaluated the dermal fibroplasia. We found a significant relationship between both architectural and cytological atypia and dermal fibroplasia by comparing the architectural and cytological atypia degree and dermal fibroplasia. As the severity of architectural and cytological atypia increased, we observed that the fibroplasia rate also increased. We suggest that as different architectural disorders and cellular changes may be seen in the same case, the architectural and cytological atypia grading should be performed separately and these atypia grades should be interpreted together.

    The scoring and grading of the degree of atypia of our cases was performed according to the criteria defined by Shea et al.26. We found a significant association and correlation between the architectural and cytological degrees of atypia in this study. Although there are many studies on grading in the literature, there is no consensus on the descriptive criteria that constitute the basis of the grading. Some of the studies degree melanocytic dysplasia by only cytological characteristics29 while others grade by both architectural and cytological characteristics23,26. Our findings show a significant relationship between architectural and cytological atypia similar to many studies in the literature. A larger number of studies with a larger number of cases are required for the standardization of grading and establishment of reliable criteria. Although we found a significant relationship between the degrees of architectural and cytological atypia in our study, we also had cases with different architectural and cytoogical atypia degrees. Although investigators report an increase in the incidence of a history of melanoma with increasing degree of dysplasia, it is possible that high grade melanocytic dysplasia cases without fibroplasia are present23. Our results support the idea that an increasing grade of melanocytic dysplasia leads to a significant increase in the presence of dermal fibroplasia.

    When grading this cytological atypia, we used the term “severe cytological atypia” in the presence of three or more nuclear criteria. We observed that dermal fibroplasia changed with the degree of cytological atypia. This finding may indicate that dermal fibroplasia may provide an additional criteria when interpreting the degree of cytological atypia in DN cases.

    The dermal fibroplasia in DN can be concentric or lamellar fashion22,25,33,34. Concentric eosinophilic fibroplasia is generally associated with melanocytic atypia or aytpical lentiginous epidermal or melanocytic hyperplasia and is most commonly seen in precursor nevi. Lamellar fibroplasia is the most prominent stromal pattern. It can also be seen with invasive melanomas6. It strongly indicates parenchymal extracellular matrix and tumor interaction. Lamellar fibroplasia indicates the end point of the progression of melanocytic precursor lesions. These changes are seen in a marked manner in lesions that are between DN and early melanoma7. Light microscopy studies have shown that the nests and melanoma nests consisting of nevus cells are surrounded by basal membrane material consisting of type-IV collagen and laminin. The basal membrane material is of varying width and has an amorphous appearance. Type-IV collagen, laminin and MMP-2 are synthesized both by melanoma cells and the neighboring fibroblasts. It is not known whether basal membrane production is mostly from melanocytic cells or fibroblasts. The interaction between basal membrane melanocytes and ECM possibly develops as a result of the backwards migration of neural crest-derived melanocytes35. This view partially explains the dermal fibroplasia found in DN cases.

    The fibroplasia is thought to develop from the interaction of some growth factors secreted by proliferated melanocytes, adjacent keratinocytes and fibroblasts with autocrine or paracrine effect36. Various stromal patterns have been defined in melanocytic dysplasia development6,37. We had no case of fibroplasia without cytological atypia in our study. The significantly increased rate of dermal fibroplasia with increasing cytological and architectural atypia supports these views. We found dermal fibroplasia together with nuclear atypia in 49 cases (52.7%). However, we did not find dermal fibroplasia despite the presence of nuclear atypia in 44 cases (47.3%). These findings indicate that the degree of stromal changes in DN can help in differentiating DN cases from other basal nevi.

    Dermal fibroplasia is a valuable marker that reflects the neoplastic cell-stroma relationship in DN cases. Evaluation of dermal fibroplasia and determining its relationship with the degree of atypia in DN cases will contribute to new studies directed towards understanding the progression risk of DN to malignant melanoma.

    ACKNOWLEDGEMENT
    We would like to thank Prof. Uğur Pabuççuoğlu, M.D., for his valuable help in writing the article.

  • Top
  • Abstract
  • Introduction
  • Methods
  • Results
  • Discussion
  • References
  • References

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  • Top
  • Abstract
  • Introduction
  • Methods
  • Results
  • Discussion
  • References
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