title: Histomorphologic assessment and interobserver diagnostic reproducibility of atypical spitzoid melanocytic neoplasms with long-term follow-up.
abstract: Predicting clinical behavior of atypical Spitz tumors remains problematic. In this study, we assessed interobserver agreement of diagnosis by 13 expert dermatopathologists for atypical Spitz tumors (n=75). We determined which histomorphologic features were most heavily weighted for their diagnostic significance by the experts and also which histomorphologic features had a statistically significant correlation with clinical outcome. There was a low interobserver agreement among the experts in categorizing lesions as malignant versus nonmalignant (κ=0.30). The histomorphologic features that were given the most diagnostic significance by the experts were: consumption of the epidermis, atypical mitoses, high-grade cytologic atypia, and mitotic rate. Conversely, the histomorphologic features that most correlated with disease progression were: frequent mitoses, deep mitoses, asymmetry, high-grade cytologic atypia, and ulceration. The presence and/or pattern of pagetoid spread, consumption of the epidermis, and lymphoid aggregates demonstrated no association with clinical behavior. The results support the assertion that there is a lack of consensus in the assessment of atypical Spitz tumors by expert dermatopathologists. Importantly, many features used to distinguish conventional melanoma from nevi were not useful in predicting the behavior of atypical Spitz tumors. This study may provide some guidance regarding histologic assessment of these enigmatic tumors.
authors.affiliation: *Department of Dermatology †Robert H. Lurie Cancer Center †††Department of Preventive Medicine and the Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, IL ‡Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY §Department of Pathology and Laboratory Medicine, Dermatopathology, UCLA Medical Center, Los Angeles ‡‡Departments of Pathology and Dermatology, University of California, San Francisco, San Francisco, CA ¶Pathology Service, Massachusetts General Hospital, Boston, MA #Department of Pathology, University of Pennsylvania, Philadelphia ¶¶Rabkin Dermatopathology Laboratory, P.C., Tarentum, PA Departments of **Pathology ††Dermatology, University of Michigan Medical Center, Ann Arbor, MI §§Department of Pathology, Section of Dermatopathology ∥∥Department of Dermatology, The University of Texas MD Anderson Cancer Center, Houston, TX ∥Department of Histopathology, Royal Surrey County Hospital & Division of Clinical Medicine, University of Surrey, Guildford, Surrey, UK ##Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Melanoma Institute Australia and The University of Sydney, NSW, Australia ***Departments of Dermatology, Chonnam National University Medical School, Gwangju, Korea.
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mesh_terms: D000328:Adult; D001315:Australia; D002648:Child; D032921:Consensus; D004817:Epidermis / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008544:Melanocytes / Q000473:pathology*; D008545:Melanoma / Q000473:pathology*; D008938:Mitosis; D008940:Mitotic Index; D060787:Neoplasm Grading; D018332:Nevus, Epithelioid and Spindle Cell / Q000473:pathology*; D015588:Observer Variation; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012878:Skin Neoplasms / Q000473:pathology*; D012883:Skin Ulcer / Q000473:pathology; D013997:Time Factors; D014481:United States; D055815:Young Adult