M. Angélica Selim

The terminology for human papillomavirus(HPV)–associated squamous lesions of the lower anogenital tract has a long history marked by disparate diagnostic terms derived from multiple specialties. It often does not reflect current knowledge of HPV biology and pathogenesis. A consensus process was convened to recommend terminology unified across lower anogenital sites. The goal was to create a histopathologic nomenclature system that reflects current knowledge of HPV biology, optimally uses available biomarkers, and facilitates clear communication across different medical specialties. The Lower Anogenital Squamous Terminology (LAST) Project was co-sponsored by the College of American Pathologists and the American Society for Colposcopy and Cervical Pathology and included 5 working groups; 3 work groups performed comprehensive literature reviews and developed draft recommendations. Another work group provided the historical background and the fifth will continue to foster implementation of the LAST recommendations. After an open comment period, the draft recommendations were presented at a consensus conference attended by LAST work group members, advisors, and representatives from 35 stakeholder organizations including professional societies and government agencies. Recommendations were finalized and voted on at the consensus meeting. The final, approved recommendations standardize biologically relevant histopathologic terminology for HPV-associated squamous intraepithelial lesions and superficially invasive squamous carcinomas across all lower anogenital tract sites and detail the appropriate use of specific biomarkers to clarify histologic interpretations and enhance diagnostic accuracy. A plan for disseminating and monitoring recommendation implementation in the practicing community was also developed. The implemented recommendations will facilitate communication between pathologists and their clinical colleagues and improve accuracy of histologic diagnosis with the ultimate goal of providing optimal patient care.

We reviewed our multicenter experience with gamma-delta (γδ) T-cell lymphomas first presenting in the skin. Fifty-three subjects with a median age of 61 years (range, 25 to 91 y) were diagnosed with this disorder. The median duration of the skin lesions at presentation was 1.25 years (range, 1 mo to 20 y). The most common presentation was deep plaques (38 cases) often resembling a panniculitis, followed by patches resembling psoriasis or mycosis fungoides (10 cases). These lesions tended to ulcerate overtime (27 cases). Single lesions or localized areas of involvement resembling cellulitis or pyoderma were reported in 8 cases. The most common anatomic site of involvement was the legs (40 cases), followed by the torso (30 cases) and arms (28 cases). Constitutional symptoms were reported in 54% (25/46) of the patients, including some with limited skin involvement. Significant comorbidities included autoimmunity (12 cases), other lymphoproliferative disorders (5 cases), internal carcinomas (4 cases), and viral hepatitis (2 cases). Lymphadenopathy (3/42 cases) and bone marrow involvement (5/28 cases) were uncommon, but serum lactose dehydrogenase (LDH) was elevated in 55% (22/39) of the patients. Abnormal positron emission tomography and/or computed tomography scans in 20/37 subjects mostly highlighted soft tissue or lymph nodes. Disease progression was associated with extensive ulcerated lesions resulting in 27 deaths including complications of hemophagocytic syndrome (4) and cerebral nervous system involvement (3). Median survival time from diagnosis was 31 months. Skin biopsies varied from a pagetoid pattern to purely dermal or panniculitic infiltrates composed of intermediate-sized lymphocytes with tissue evidence of cytotoxicity. The most common immunophenotype was CD3+/CD4⁻/CD5⁻/CD8⁻/BF1⁻/γ-M1+/TIA-1+/granzyme-B+/CD45RA-/CD7-, and 4 cases were Epstein-Barr virus positive. This is the largest study to date of cutaneous γδ T-cell lymphomas and demonstrates a variety of clinical and pathologic presentations with a predictable poor outcome.

Melanoma diagnosis is clinically challenging: the accuracy of visual inspection by dermatologists is highly variable and heavily weighted toward false positives. Even the current gold standard of biopsy results in varying diagnoses among pathologists. We have developed a multiphoton technique (based on pump-probe spectroscopy) that directly determines the microscopic distribution of eumelanin and pheomelanin in pigmented lesions of human skin. Our initial results showed a marked difference in the chemical variety of melanin between nonmalignant nevi and melanoma, as well as a number of substantial architectural differences. We examined slices from 42 pigmented lesions and found that melanomas had an increased eumelanin content compared to nonmalignant nevi. When used as a diagnostic criterion, the ratio of eumelanin to pheomelanin captured all investigated melanomas but excluded three-quarters of dysplastic nevi and all benign dermal nevi. Additional evaluation of architectural and cytological features revealed by multiphoton imaging, including the maturation of melanocytes, presence of pigmented melanocytes in the dermis, number and location of melanocytic nests, and confluency of pigmented cells in the epidermis, further increased specificity, allowing rejection of more than half of the remaining false-positive results. We then adapted this multiphoton imaging technique to hematoxylin and eosin (H&E)-stained slides. By adding melanin chemical contrast to H&E-stained slides, pathologists will gain complementary information to increase the ease and accuracy of melanoma diagnosis.