Reproduction of patterns in melanocytic proliferations by agent-based simulation and geometric modeling

Spatio-temporal patterns of melanocytic proliferations observed in vivo are important for diagnosis but the mechanisms that produce them are poorly understood. Here we present an agent-based model for simulating the emergence of the main biologic patterns found in melanocytic proliferations. Our model portrays the extracellular matrix of the dermo-epidermal junction as a two-dimensional manifold and we simulate cellular migration in terms of geometric translations driven by adhesive, repulsive and random forces. Abstracted cellular functions and melanocyte-matrix interactions are modeled as stochastic events. For identification and validation we use visual renderings of simulated cell populations in a horizontal perspective that reproduce growth patterns observed in vivo by sequential dermatoscopy and corresponding vertical views that reproduce the arrangement of melanocytes observed in histopathologic sections. Our results show that a balanced interplay of proliferation and migration produces the typical reticular pattern of nevi, whereas the globular pattern involves additional cellular mechanisms. We further demonstrate that slight variations in the three basic cellular properties proliferation, migration, and adhesion are sufficient to produce a large variety of morphological appearances of nevi. We anticipate our model to be a starting point for the reproduction of more complex scenarios that will help to establish functional connections between abstracted microscopic behavior and macroscopic patterns in all types of melanocytic proliferations including melanoma.

Ex vivo dermoscopy of cutaneous biopsies for melanocytic neoplasms: a retrospective review of 517 cases with histopathologic correlation

Clinical dermoscopy has provided new insights into the diagnosis and classification of melanocytic neoplasms. There are only limited data on its applications in dermatopathology. In our laboratory, we routinely photograph all skin biopsies with ex vivo dermoscopy (EVD). We retrospectively reviewed 517 cutaneous biopsies with corresponding EVD images to determine whether EVD provides useful ancillary information in the histopathologic diagnosis of melanocytic neoplasms. Four hundred eighty-three cases (93.4%) yielded usable images. The lesions could be categorized according to a published dermoscopic classification system of melanocytic proliferations. Reticular pigmentation correlated with dysplastic nevi, globular pigmentation with congenital nevi, homogenous blue pigmentation with blue nevi, starburst peripheral globular pigmentation with Spitz nevi, and atypical pigment patterns with melanoma. Eighteen of 25 cases (72%) with ambiguous histopathology were assigned a more definite diagnosis when reviewed contemporaneously with EVD images. The surgical margins in 40 cases (7.7%) were reclassified when EVD images were included in the review. We found EVD to be a useful technique and advocate its use for diagnosis and clinical-pathologic correlation.

Dermoscopy of pigmented lesions of the vulva: a retrospective morphological study

BACKGROUND

The dermoscopic patterns of pigmented skin tumors are influenced by the body site.

OBJECTIVE

To evaluate the clinical and dermoscopic features associated with pigmented vulvar lesions.

METHODS

Retrospective analysis of clinical and dermoscopic images of vulvar lesions. The χ² test was used to test the association between clinical data and histopathological diagnosis.

RESULTS

A total of 42 (32.8%) melanocytic and 86 (67.2%) nonmelanocytic vulvar lesions were analyzed. Nevi significantly prevailed in younger women compared with melanomas and melanosis and exhibited most commonly a globular/cobblestone (51.3%) and a mixed (21.6%) pattern. Dermoscopically all melanomas showed a multicomponent pattern. Melanotic macules showed clinical overlapping features with melanoma, but their dermoscopic patterns differed significantly from those observed in melanomas.

CONCLUSION

The diagnosis and management of pigmented vulvar lesions should be based on a good clinicodermoscopic correlation. Dermoscopy may be helpful in the differentiation of solitary melanotic macules from early melanoma.