RESUMO
Dermatologic reactions are among the most common adverse events of antiprogrammed cell death-1 (anti-PD-1) monoclonal antibodies agents and include maculopapular rash, psoriasiform rash, lichenoid eruptions, autoimmune bullous disorders, and vitiligo. Here, we present a case of a 12-year-old African American male with metastatic spitzoid melanoma treated with nivolumab who developed a mild lichenoid eruption that progressed to a severe case of lichen planus pemphigoides (LPP). Management was complex given the patient's age and history and included hospitalization for intravenous steroids, an intensive topical steroid regimen, methotrexate, and discontinuation of nivolumab. This case illustrates a rare but dramatic progression from a mild LP-like eruption to severe bullous lichenoid eruption, most consistent with LPP, as well as the diagnostic and treatment challenges in the setting of a pediatric patient on nivolumab.
Assuntos
Doenças Autoimunes , Exantema , Líquen Plano , Erupções Liquenoides , Melanoma , Dermatopatias Vesiculobolhosas , Humanos , Masculino , Criança , Nivolumabe/efeitos adversos , Líquen Plano/induzido quimicamente , Líquen Plano/diagnóstico , Erupções Liquenoides/induzido quimicamente , Melanoma/tratamento farmacológico , Exantema/induzido quimicamenteRESUMO
ABSTRACT: "Lipodissolve" (LD) is a non-FDA-approved solution of phosphatidylcholine in deoxycholate that was developed around 2004. A study of its safety reported minor and uncommon side effects including pain, tender nodules, pigmentary alterations, and ulceration at the site of injection. We present a 53-year-old woman who received LD injections bilaterally to her proximal arms. One week later, she developed painful nodules at each injection site. She was treated with a 10-day course of trimethoprim/sulfamethoxazole without improvement. An incisional biopsy was performed and showed deep dermal suppurative inflammation with numerous neutrophils and granulomas. Stains for bacteria, fungus, and acid-fast organisms were negative. Cultures for acid-fast bacilli grew Mycobacterium abscessus, sensitive to amikacin and clarithromycin. The patient was subsequently treated with intravenous amikacin, azithromycin, and bedaquiline with symptom resolution. Investigation revealed 3 similar infections linked to LD injections originating from the same physician's office. The most common organism implicated in injection infections is Staphylococcus aureus. Infections at injection sites caused by atypical mycobacteria have been reported to occur after tattooing, other types of injections, and implants. Of atypical mycobacteria, M. abscessus accounts for the greatest number of postinjection or iatrogenic infections. Common antitubercular drugs are not effective for treating atypical mycobacteria, making species identification and sensitivity testing imperative for treatment. This case highlights an unusual infection caused by cosmetic injections of LD, previously reported to be associated with minimal side effects, and the importance of examination for acid-fast bacilli and follow-up with culture, even in the absence of organisms identified on stained sections.
Assuntos
Tecido Adiposo , Infecções por Mycobacterium não Tuberculosas/diagnóstico , Mycobacterium abscessus/isolamento & purificação , Antibacterianos/uso terapêutico , Braço , Técnicas Cosméticas/efeitos adversos , Infecção Hospitalar/diagnóstico , Diagnóstico Diferencial , Feminino , Humanos , Injeções/efeitos adversos , Pessoa de Meia-Idade , Infecções por Mycobacterium não Tuberculosas/tratamento farmacológico , Infecções por Mycobacterium não Tuberculosas/etiologiaRESUMO
BACKGROUND: Current staging systems for cutaneous squamous cell carcinoma (cSCC) incorporate histologic grade. There are no universally agreed on criteria to define differentiation for cSCC. OBJECTIVE: To determine the interrater and intrarater reliability among dermatopathologists and Mohs surgeons in grading histological differentiation for cSCC. METHODS AND MATERIALS: One hundred thirty-one archived slides were selected. Three dermatopathologists and 3 Mohs surgeons graded the tumors in a blinded manner (Round 1). In an attempt to improve concordance, all 6 participants were then asked to regrade the tumors based on a devised quantitative grading scale (Round 2). RESULTS: For Round 1, overall κ was 0.56 corresponding to a weak agreement. κ for well, moderate, and poorly differentiated tumors was 0.68, 0.39, and 0.59, respectively, corresponding to moderate, minimal, and weak concordance. For Round 2 of the study, overall κ was 0.60, with κ = 0.75, 0.46, and 0.61 for well, moderate, and poorly differentiated tumors, respectively. Overall intrarater reliability was 0.70 (κ = 0.70, 0.77, 0.68, 0.71, 0.56, and 0.75), corresponding to a moderate concordance. CONCLUSION: Overall concordance for cSCC histologic grading is weak to moderate among the experimental group. Substantial differences in concordance exist among histological degrees of differentiation, with lowest agreement in moderately differentiated tumors.
Assuntos
Carcinoma de Células Escamosas/patologia , Dermatologia , Patologia Clínica , Neoplasias Cutâneas/patologia , Oncologia Cirúrgica , Humanos , Cirurgia de Mohs , Gradação de Tumores , Variações Dependentes do Observador , Reprodutibilidade dos TestesRESUMO
ABSTRACT: Cutaneous eruptions associated with hemophagocytic lymphohistiocytosis (HLH) have been reported in 6%-63% of patients. Clinical findings of these skin lesions vary widely and include maculopapular rashes, ulcers, and violaceous nodules. Corresponding histologic findings are also variable and are considered nonspecific. We report the case of a 4-year-old boy who initially developed a widespread popular-pustular rash 2 weeks after his 12-month measles, mumps, and rubella vaccinations. These resolved with scarring then recurred following his 24-month vaccinations. Multiple skin biopsies were negative for infectious organisms and showed a granulomatous infiltrate with perforation and necrobiosis. The differential diagnosis included perforating granuloma annulare, infection, or rheumatoid nodules. At the age of 4, he developed fever, hepatosplenomegaly, pancytopenia and other laboratory abnormalities, requiring hospitalization. A number of studies were performed including biopsies of bone marrow and liver. Molecular testing revealed 2 mutations in UNC13D known to be associated with familial HLH. His prior cutaneous lesions were likely caused by immune dysregulation exacerbated by immunizations because of underlying familial HLH. This case illustrates the importance of recognizing an unusual cutaneous manifestation of a rare disease to arrive at an earlier diagnosis in a pediatric patient. Although cutaneous eruptions usually develop concurrently with other systemic symptoms of HLH, preceding unusual skin lesions may be the first indication of this rare disease.
Assuntos
Toxidermias/genética , Linfo-Histiocitose Hemofagocítica/complicações , Proteínas de Membrana/genética , Vacinas/efeitos adversos , Pré-Escolar , Dermatite/patologia , Granuloma/patologia , Humanos , Linfo-Histiocitose Hemofagocítica/genética , Masculino , MutaçãoRESUMO
Prurigo pigmentosa is a rare inflammatory cutaneous disorder associated with ketosis that resolves with reticulate hyperpigmentation. A 19-year-old man was admitted to the hospital with diabetic ketoacidosis. He also had developed reticulate papules coalescing into plaques over the posterior neck, back, and abdomen. Histopathological findings consistent with the clinical findings suggested the diagnosis of prurigo pigmentosa. After treatment with topical triamcinolone and oral doxycycline along with resolution of his ketosis after insulin administration, the patient's rash healed with reticulate hyperpigmentation.
Assuntos
Diabetes Mellitus , Cetoacidose Diabética , Hiperpigmentação , Cetose , Prurigo , Adulto , Cetoacidose Diabética/complicações , Cetoacidose Diabética/diagnóstico , Cetoacidose Diabética/tratamento farmacológico , Doxiciclina/uso terapêutico , Humanos , Hiperpigmentação/complicações , Hiperpigmentação/etiologia , Cetose/complicações , Cetose/tratamento farmacológico , Masculino , Prurigo/diagnóstico , Prurigo/tratamento farmacológico , Prurigo/etiologia , Adulto JovemRESUMO
Pyoderma gangrenosum (PG) is an inflammatory, ulcerative condition that is characterized by painful ulcers that commonly present on the lower extremities. Up to half of PG cases are associated with underlying systemic disease, including inflammatory bowel disease, various autoimmune conditions, and malignancy. Another well-known association is the manifestation of PG with recreational cocaine use, especially cocaine contaminated with the adulterant agent levamisole. Once utilized for its immunomodulatory capabilities, levamisole was withdrawn from the market in 2002. It has since been repurposed to potentiate the amphetamine-like effects and duration of cocaine and has reduced preparation cost. We present a 52-year-old woman with chronic maxillary sinusitis and cocaine use disorder presenting with a two-week history of painful ulcers on bilateral lower extremities, each with a purulent base and undermined, violaceous borders. Urine toxicology was positive for cocaine and serologic studies were positive for cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) and lupus anticoagulant. Underlying conditions, especially that of granulomatosis with polyangiitis, were considered and ultimately ruled out. The patient's lesions exhibited a marked response with a short course of oral corticosteroids, typical of PG associated with levamisole. This case highlights the crucial role that drug abstinence plays in the prevention of recurrence.
Assuntos
Anticorpos Anticitoplasma de Neutrófilos/sangue , Transtornos Relacionados ao Uso de Cocaína/complicações , Contaminação de Medicamentos , Levamisol/efeitos adversos , Pioderma Gangrenoso/induzido quimicamente , Pioderma Gangrenoso/imunologia , Corticosteroides/uso terapêutico , Betametasona/análogos & derivados , Betametasona/uso terapêutico , Doença Crônica , Diagnóstico Diferencial , Feminino , Humanos , Sinusite Maxilar/complicações , Pessoa de Meia-Idade , Prednisona/uso terapêutico , Pioderma Gangrenoso/tratamento farmacológico , Pioderma Gangrenoso/patologiaRESUMO
Telomerase reverse transcriptase (TERT) promoter mutations are commonly found in malignant melanomas but rare in melanocytic nevi. To assess its potential diagnostic utility for the distinction of melanoma from nevus, we determined the TERT promoter mutation status of 86 primary melanomas, 72 melanocytic nevi, and 40 diagnostically problematic melanocytic proliferations. Of the 86 melanomas, 67 (77.9%) were TERT-positive, defined as harboring a hotspot TERT promoter mutation at positions -124C>T, -124_125CC>TT, -138_139CC>TT, or -146C>T. Of the 72 nevi, only 1 (1.4%) was TERT-positive. Of the 40 diagnostically uncertain melanocytic proliferations, 2 (5.0%) were TERT-positive. TERT positivity as a test for melanoma versus nevus had an accuracy of 87.3% [95% confidence interval (CI), 81.1-92.1], a sensitivity of 77.9% (95% CI, 68.9-85.4), a specificity of 98.6% (95% CI, 95.8-100), a positive predictive value of 98.5% (95% CI, 95.6-100), and a negative predictive value of 78.9% (95% CI, 72.6-85.4). Our results indicate that hotspot TERT promoter mutation status may be a useful ancillary parameter for the diagnosis of melanoma. In particular, the high specificity of these mutations for melanoma indicates the presence of a TERT promoter mutation in a melanocytic neoplasm associated with diagnostic controversy, or uncertainty should increase concern for a melanoma.
Assuntos
Melanoma/diagnóstico , Melanoma/genética , Regiões Promotoras Genéticas/genética , Neoplasias Cutâneas/diagnóstico , Neoplasias Cutâneas/genética , Telomerase/genética , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Nevo Pigmentado/diagnóstico , Nevo Pigmentado/genética , Melanoma Maligno CutâneoRESUMO
BACKGROUND: Pigmented epithelioid melanocytoma (PEM) is an uncommon, recently described entity with unknown biologic behavior. There is a high rate of regional metastases, but limited evidence of distant metastases or disease-related death. OBJECTIVE: We sought to report our series of patients given a diagnosis of PEM at our institution and provide mutational analysis of genes commonly implicated in melanoma in 2 cases. METHODS: The pathology database was queried for cases of PEM diagnosed at the University of Rochester. Charts were reviewed for follow-up information. Mutational analysis of melanoma-associated genes was performed on 2 cases. RESULTS: Nine cases of PEM were retrieved in a 10-year retrospective review. Five patients underwent sentinel lymph node biopsy with 3 of 5 having a positive sentinel lymph node. All 9 patients are alive and disease-free with average follow-up of 38.75 months. Two tumors were tested for common melanoma-associated mutations, and were negative, except for a telomerase reverse transcriptase promoter deletion detected in 1 sample. The deletion has not been associated with melanoma, and therefore its biologic significance is unclear. LIMITATIONS: Small sample size, retrospective nature, and single institution experience are limitations. CONCLUSIONS: PEM appears to have an indolent behavior. However, currently the evidence is too limited to provide insight into its true biologic potential.
Assuntos
Melanoma/secundário , Nevo Azul/patologia , Neoplasias Cutâneas/patologia , Adolescente , Adulto , Criança , Pré-Escolar , Análise Mutacional de DNA , Feminino , Humanos , Metástase Linfática , Masculino , Melanoma/genética , Melanoma/cirurgia , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Regiões Promotoras Genéticas , Estudos Retrospectivos , Biópsia de Linfonodo Sentinela , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/cirurgia , Taxa de Sobrevida , Telomerase/genética , Adulto JovemRESUMO
BACKGROUND: Previously, using imaging mass spectrometry (IMS), we discovered proteomic differences between Spitz nevi and Spitzoid melanomas. OBJECTIVE: We sought to determine whether IMS can assist in the classification of diagnostically challenging atypical Spitzoid neoplasms (ASN), to compare and correlate the IMS and histopathological diagnoses with clinical behavior. METHODS: We conducted a retrospective collaborative study involving centers from 11 countries and 11 US institutions analyzing 102 ASNs by IMS. Patients were divided into clinical groups 1 to 4 representing best to worst clinical behavior. The association among IMS findings, histopathological diagnoses, and clinical groups was assessed. RESULTS: There was a strong association between a diagnosis of Spitzoid melanoma by IMS and lesions categorized as clinical groups 2, 3, and 4 (recurrence of disease, metastases, or death) compared with clinical group 1 (no recurrence or metastasis beyond a sentinel node) (P < .0001). Older age and greater tumor thickness were strongly associated with poorer outcome (P = .01). CONCLUSIONS: IMS diagnosis of ASN better predicted clinical outcome than histopathology. Diagnosis of Spitzoid melanoma by IMS was strongly associated with aggressive clinical behavior. IMS analysis using a proteomic signature may improve the diagnosis and prediction of outcome/risk stratification for patients with ASN.
Assuntos
Espectrometria de Massas , Melanoma/diagnóstico por imagem , Melanoma/secundário , Recidiva Local de Neoplasia/diagnóstico por imagem , Recidiva Local de Neoplasia/patologia , Nevo de Células Epitelioides e Fusiformes/diagnóstico por imagem , Nevo de Células Epitelioides e Fusiformes/patologia , Neoplasias Cutâneas/diagnóstico por imagem , Neoplasias Cutâneas/patologia , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Diagnóstico Diferencial , Feminino , Humanos , Metástase Linfática , Masculino , Melanoma/química , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/química , Nevo de Células Epitelioides e Fusiformes/química , Proteínas/análise , Estudos Retrospectivos , Medição de Risco , Biópsia de Linfonodo Sentinela , Neoplasias Cutâneas/química , Resultado do Tratamento , Carga Tumoral , Adulto JovemRESUMO
Cutaneous squamous cell carcinoma (SCC) with osteoclast-like giant cells (hereafter, osteoclastic cells) is very rare; eight cases have been reported since 2006. Whether the osteoclastic cells represents a reactive or neoplastic change remains a matter of debate. Osteoclastic cells are often observed in the sarcomatous component of cutaneous carcinosarcoma. SCC with osteoclastic cells is a heterogeneous condition that includes SCC with stromal changes containing osteoclastic cells (also known as osteoclast-like giant cell reaction) and carcinosarcoma. In some cases, SCC with an associated osteoclast-like giant cell reaction has been differentiated from carcinosarcoma based on the degree of cytologic atypia in non-epithelial components. We summarized the clinical and histopathologic characteristics of 11 patients of SCC with osteoclastic cells, including our two cases of SCC with an osteoclast-like giant cell reaction and one case of carcinosarcoma. The affected patients were old and more likely to be male (64%). Seven cases (64%) were in the head and neck. Moreover, multiple features of high risk SCC were observed, such as a tumor size greater than 2 cm (56%), moderate or poor differentiation (100%), recurrence (33%) and nodal metastasis (17%) after excision and immunosuppression (27%). Interestingly, half of the previously reported cases of SCC with osteoclastic giant cell reaction had histopathologic findings that were overlapping with those of carcinosarcoma.
Assuntos
Carcinoma de Células Escamosas , Carcinossarcoma , Células Gigantes , Neoplasias de Cabeça e Pescoço , Osteoclastos , Neoplasias Cutâneas , Idoso , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patologia , Carcinossarcoma/metabolismo , Carcinossarcoma/patologia , Feminino , Células Gigantes/metabolismo , Células Gigantes/patologia , Neoplasias de Cabeça e Pescoço/metabolismo , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Masculino , Osteoclastos/metabolismo , Osteoclastos/patologia , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologiaRESUMO
Lymphomatoid papulosis (LyP) is a cutaneous CD30-positive T-cell lymphoproliferative disorder that occurs primarily in adults and presents with crops of papules that become necrotic and spontaneously regress. It is classified according to the histopathologic findings; currently recognized subtypes include A, B, C, D, and E. LyP is uncommon in children. Herein we describe a child with an unusual clinical presentation of LyP type D and review the literature of reported cases in children.
Assuntos
Papulose Linfomatoide/diagnóstico , Neoplasias Cutâneas/patologia , Pele/patologia , Adolescente , Criança , Diagnóstico Diferencial , Humanos , MasculinoRESUMO
Plexin B1, the receptor for Semaphorin 4D (Sema4D), is expressed by melanocytes in the skin. We recently showed that Sema4D suppresses activation of the hepatocyte growth factor receptor, MET, in melanocytes, and that knockdown of Plexin B1 results in activation of MET. MET signaling mediates proliferation, survival and migration in melanocytes, and its activation is associated with transformation of melanocytes to melanoma. In this report we investigated the mechanism by which Plexin B1 inhibits MET activation. Our results show that Plexin B1 and MET exist as an oligomeric receptor-receptor complex in melanocytes, and that receptor association is increased by Sema4D. MET and Plexin B1 receptor complexes were identified along the cell body of melanocytes, and Sema4D increased receptor association on dendrites, suggesting that Sema4D regulates MET-dependent processes at precise locations on the melanocyte. Despite activation of MET, Plexin B1 knockdowns proliferated slowly and showed increased apoptosis compared with controls. Shp2, a non-receptor protein tyrosine phosphatase, translates growth and survival signals from MET and other receptor tyrosine kinases. Plexin B1 knockdowns had markedly lower levels of Shp2 compared with controls, and Sema4D upregulated Shp2 expression at the protein and message level in normal melanocytes. Functional studies showed that blockade of Shp2 activity abrogated MET-dependent activation of Erk1/Erk2 and Akt in melanocytes. These results suggest a complex role for Sema4D and Plexin B1 in orchestrating signaling from the MET receptor in melanocytes. Because Shp2 is a downstream adaptor protein for multiple receptors, Sema4D may control the effects of several growth factors on melanocytes through regulation of Shp2.
Assuntos
Melanócitos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 11/biossíntese , Proteínas Proto-Oncogênicas c-met/metabolismo , Receptores de Superfície Celular/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Antígenos CD/metabolismo , Movimento Celular/fisiologia , Humanos , Melanócitos/citologia , Proteínas do Tecido Nervoso/genética , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 11/genética , Proteína Tirosina Fosfatase não Receptora Tipo 11/metabolismo , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-met/genética , Receptores de Superfície Celular/genética , Semaforinas/metabolismo , Transdução de SinaisRESUMO
BACKGROUND: In January 2012, on the basis of an initial report from a dermatologist, we began to investigate an outbreak of tattoo-associated Mycobacterium chelonae skin and soft-tissue infections in Rochester, New York. The main goals were to identify the extent, cause, and form of transmission of the outbreak and to prevent further cases of infection. METHODS: We analyzed data from structured interviews with the patients, histopathological testing of skin-biopsy specimens, acid-fast bacilli smears, and microbial cultures and antimicrobial susceptibility testing. We also performed DNA sequencing, pulsed-field gel electrophoresis (PFGE), cultures of the ink and ingredients used in the preparation and packaging of the ink, assessment of source water and faucets at tattoo parlors, and investigation of the ink manufacturer. RESULTS: Between October and December 2011, a persistent, raised, erythematous rash in the tattoo area developed in 19 persons (13 men and 6 women) within 3 weeks after they received a tattoo from a single artist who used premixed gray ink; the highest occurrence of tattooing and rash onset was in November (accounting for 15 and 12 patients, respectively). The average age of the patients was 35 years (range, 18 to 48). Skin-biopsy specimens, obtained from 17 patients, showed abnormalities in all 17, with M. chelonae isolated from 14 and confirmed by means of DNA sequencing. PFGE analysis showed indistinguishable patterns in 11 clinical isolates and one of three unopened bottles of premixed ink. Eighteen of the 19 patients were treated with appropriate antibiotics, and their condition improved. CONCLUSIONS: The premixed ink was the common source of infection in this outbreak. These findings led to a recall by the manufacturer.
Assuntos
Cosméticos/efeitos adversos , Surtos de Doenças , Tinta , Infecções por Mycobacterium não Tuberculosas/etiologia , Mycobacterium chelonae/isolamento & purificação , Tatuagem/efeitos adversos , Feminino , Humanos , Masculino , Infecções por Mycobacterium não Tuberculosas/epidemiologia , Mycobacterium chelonae/genética , New York/epidemiologia , Análise de Sequência de DNA , Pele/microbiologia , Pele/patologiaRESUMO
Telomerase is frequently expressed in cancer and contributes to carcinogenesis. Two recent publications report the identification of a set of recurrent mutations in melanoma in the promoter of the telomerase reverse transcriptase gene (TERT) that appears to be the result of mutagenesis from ultraviolet (UV) radiation. Both groups reported that the mutations increase the transcription of TERT. This prompted our search for similar mutations in two other UV-related skin cancers, basal cell carcinoma, and squamous cell carcinoma. We found that the activating TERT promoter mutations reported in melanoma are also frequent in squamous cell carcinoma (50%) and basal cell carcinoma, the latter including both sporadic tumors (78%) and tumors from patients with nevoid basal cell carcinoma syndrome (68%). These mutations were found in only 1 of 11 Bowen's disease (squamous cell carcinoma in situ) specimens, and in none of 15 non-malignant skin specimens and 57 blood specimens. The mutations were frequently homozygous or hemizygous, with little or no normal signal at the mutated positions. These data suggest that TERT promoter mutations are the most frequent putative oncogenic mutations in cutaneous cancer.
Assuntos
Doença de Bowen/genética , Carcinoma Basocelular/genética , Mutação , Regiões Promotoras Genéticas , Neoplasias Cutâneas/genética , Telomerase/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Doença de Bowen/enzimologia , Doença de Bowen/patologia , Carcinoma Basocelular/enzimologia , Carcinoma Basocelular/patologia , Análise Mutacional de DNA , Feminino , Heterozigoto , Homozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Cutâneas/enzimologia , Neoplasias Cutâneas/patologiaRESUMO
Melanocytes are pigment producing cells that arise from the neural crest and migrate to the skin early in fetal development. The pigment that melanocytes synthesize, melanin, plays a critical role in protecting the skin from mutagenic ultraviolet irradiation. Melanocytes are also precursor cells for melanoma, a deadly form of skin cancer. Because melanocytes make up a minority population of cells in the epidermis they have been difficult to propagate in culture. The landmark paper by Eisinger and Marko, described below, was the first successful report of large scale propagation of pure cultures of melanocytes. This paper set the stage for an explosive growth in knowledge in the biology of human melanocytes and allowed scientists to begin dissecting the different oncogenic events involved in the transition of melanocytes to melanoma.