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Timothy M Johnson

Publications and source records attributed to Timothy M Johnson.

At least 19 recordsLinked to original sources
PubMed2007

The impact of factors beyond Breslow depth on predicting sentinel lymph node positivity in melanoma.

BACKGROUND: In addition to Breslow depth, the authors previously described how increasing mitotic rate and decreasing age predicted sentinel lymph node (SLN) metastases in patients with melanoma. The objectives of the current study were to verify those previous results and to create a prediction model for the better selection of which patients with melanoma should undergo SLN biopsy. METHODS: The authors reviewed 1130 consecutive patients with melanoma in a prospective database who underwent successful SLN biopsy. After eliminating patients aged <16 years and patients who had melanomas that measured <1 mm, 910 remaining patients were reviewed for clinical and pathologic features and positive SLN status. Univariate association of patient and tumor characteristics with positive SLN status was explored by using standard logistic regression techniques, and the best multivariate model that predicted lymph node metastases was constructed by using a backward stepwise-elimination technique. RESULTS: The characteristics that were associated significantly with lymph node metastasis were angiolymphatic invasion, the absence of regression, increasing mitotic rate, satellitosis, ulceration, increasing Breslow depth, decreasing age, and location (trunk or lower extremity compared with upper extremity or head/neck). Previously reported interactions between mitotic rate and age and between Breslow depth and age were confirmed. The best multivariate model included patient age (linear), angiolymphatic invasion, the number of mitoses (linear), the interaction between patient age and the number of mitoses, Breslow depth (linear), the interaction between patient age and Breslow depth, and primary tumor location. CONCLUSIONS: Younger age, increasing mitotic rate (especially in younger patients), increasing Breslow depth (especially in older patients), angiolymphatic invasion, and trunk or lower extremity location of the primary tumor were associated with a greater likelihood of positive SLN status. The current results support the use of factors beyond Breslow depth to determine the risk of positive SLN status in patients with cutaneous melanoma.

Adult↗
PubMed2006

Anti-oncogenic role of the endoplasmic reticulum differentially activated by mutations in the MAPK pathway.

Dysfunction of the endoplasmic reticulum (ER) has been reported in a variety of human pathologies, including cancer. However, the contribution of the ER to the early stages of normal cell transformation is largely unknown. Using primary human melanocytes and biopsies of human naevi (moles), we show that the extent of ER stress induced by cellular oncogenes may define the mechanism of activation of premature senescence. Specifically, we found that oncogenic forms of HRAS (HRAS(G12V)) but not its downstream target BRAF (BRAF(V600E)), engaged a rapid cell-cycle arrest that was associated with massive vacuolization and expansion of the ER. However, neither p53, p16(INK4a) nor classical senescence markers--such as foci of heterochromatin or DNA damage--were able to account for the specific response of melanocytes to HRAS(G12V). Instead, HRAS(G12V)-driven senescence was mediated by the ER-associated unfolded protein response (UPR). The impact of HRAS on the UPR was selective, as it was poorly induced by activated NRAS (more frequently mutated in melanoma than HRAS). These results argue against premature senescence as a converging mechanism of response to activating oncogenes and support a direct role of the ER as a gatekeeper of tumour control.

Cell Cycle↗
PubMed2006

Significance of multiple lymphatic basin drainage in truncal melanoma patients undergoing sentinel lymph node biopsy.

BACKGROUND: Truncal melanoma involving metastases to multiple lymph node basins has a much worse prognosis than tumor involvement of a single lymph node basin. Recent results also suggest that, independently of the status of lymph node involvement, patients with multiple lymphatic basin drainage (MLBD) on lymphoscintigraphy have an increased risk of lymph node metastasis and a worse prognosis than those with a single lymphatic drainage basin. Because published reports have conflicting results, the authors compared their experience at the University of Michigan Comprehensive Cancer Center with recently published findings. METHODS: The authors searched a prospectively maintained melanoma database at the University of Michigan for patients with primary truncal melanoma who underwent lymphoscintigraphy and sentinel lymph node biopsy between 1997 and 2004. The association of MLBD with the clinical and pathologic characteristics collected and the presence of regional metastases was tested by using contingency tables and the chi(2) test statistic and by using the Fisher's exact test statistic when cell frequencies were small. The product-limit method of Kaplan and Meier was used to estimate disease-free and overall survival probabilities. RESULTS: Of 423 patients with primary truncal melanoma who underwent sentinel lymph node biopsy, 123 (29%) had a positive result, and 98 patients (23.2%) had MLBD. Patients with tumors located in the middle of the trunk and tumor ulceration were more likely to have MLBD (P < .0001 and P = .045, respectively). Patients with a single lymphatic drainage basin and MLBD had a similar risk of lymph node metastasis and similar disease-free and overall survival. CONCLUSIONS: Patients with truncal melanomas tend to have MLBD when the tumor is located in the middle of the trunk or when ulceration is present. In our experience, drainage to multiple lymphatic basins was not an independent risk factor for sentinel lymph node metastasis and has no independent prognostic significance.

Adolescent↗
PubMed2006

BRAF and NRAS mutations in spitzoid melanocytic lesions.

BRAF mutations are common events in a variety of melanocytic nevi and primary cutaneous melanomas. We have previously found BRAF mutations in 82% of nevi, consisting of congenital, common acquired and dysplastic types, and 33% of primary cutaneous melanomas other than the spitzoid type, similar to other published reports. A small number of studies have evaluated Spitz nevi and have failed to detect any lesions possessing a BRAF mutation. Only one study included categories of atypical Spitz nevus and borderline lesions suspected to be spitzoid melanomas, along with classic Spitz nevi and spitzoid melanomas. We examined a spectrum of spitzoid lesions that included 48 Spitz nevi, some with atypical features, seven atypical (borderline) Spitz tumors, and 13 spitzoid melanomas. BRAF mutations were detected in 12 of 68 spitzoid lesions, of which two were spitzoid melanomas and 10 were Spitz nevi. Five of the 10 Spitz nevi with BRAF mutations were altered by more than usual cytologic atypia and/or architectural atypia overlapping with dysplastic nevi, or irritation/inflammation; one desmoplastic Spitz nevus had a BRAF mutation. These results indicate that a small subset of Spitz nevi, some with atypical histologic features, possess BRAF mutations. Therefore, the BRAF mutational status does not separate all Spitz nevi from spitzoid melanomas and non-Spitz types of melanocytic proliferations, contrary to previous reports.

Adolescent↗
PubMed2006

The effects of laser-mediated hair removal on immunohistochemical staining properties of hair follicles.

BACKGROUND: The mechanisms involved in laser-mediated hair removal remain unclear. One means of reducing hair growth is alteration of follicular stem cells. OBJECTIVE: We sought to examine the effects of laser hair removal on the immunohistochemical staining properties of human hair follicles, including the putative stem cells of the bulge region. METHODS: Treatment of unwanted axillary hair was performed on one side using an 800 nm-wavelength diode laser and on the other side using a 1064 nm-wavelength neodymium:yttrium-aluminum-garnet laser. Serial skin samples were obtained at baseline and various times after treatment and stained using immunohistochemical techniques. RESULTS: Hair shafts were thermally altered, but the immunostaining properties of much of the follicle, including the bulge region, remained generally unchanged. LIMITATIONS: This study only addressed the acute immunohistochemical changes found after a single treatment using specific laser parameters. CONCLUSIONS: Laser-mediated hair removal does not appear to work by frank destruction of follicular stem cells. Other mechanisms including functional alteration of these cells may underlie the clinical efficacy of the procedure.

Adult↗
PubMed2006

Prevalence of psychotropic medication use among cosmetic and medical dermatology patients: a comparative study.

BACKGROUND: Little is known about the psychologic status of cosmetically oriented dermatology patients. OBJECTIVE: We sought to determine the prevalence of psychotropic medication use among such patients to offer insight into the rates of psychopathology in this group. METHODS: We conducted a retrospective chart review of patients seeking consultation at a cosmetic dermatology practice, recorded patients' use of psychotropic medicines, and compared this with data from a control group of medical dermatology patients. RESULTS: Both groups reported rates of psychotropic medication use above those expected in the general population. There was no statistically significant difference in the prevalence of psychotropic drug use between cosmetic (18%) and medical (17%) dermatology patients. LIMITATIONS: There is not a one-to-one correspondence between psychotropic medication use and the presence of psychopathology. Data are based on patient health histories and, thus, may be subject to underreporting. CONCLUSIONS: There is a relatively high rate of psychotropic drug use among all patients seeking care from dermatologists, but this does not appear to be more common among patients interested in undergoing cosmetic procedures.

Adult↗
PubMed2006

Microdermabrasion with and without aluminum oxide crystal abrasion: a comparative molecular analysis of dermal remodeling.

BACKGROUND: Microdermabrasion is a popular method of superficial skin resurfacing with effects on dermal remodeling. OBJECTIVE: The purpose of this study was to evaluate the relative importance of the two components of microdermabrasion, negative pressure and abrasion, in stimulating expression of key genes involved in dermal remodeling. METHODS: Ten subjects were treated with a microdermabrasion machine using focal crystal abrasion and negative pressure or negative pressure alone for 3 seconds. Serial biochemical analyses were performed. Reverse transcriptase real-time polymerase chain reaction assays were used to evaluate changes in transcription factor activator protein-1, primary cytokines (interleukin 1beta, tumor necrosis factor-alpha), and matrix metalloproteinases (MMP-1, MMP-3, MMP-9). RESULTS: Significant increases in gene expression of the c-Jun component of activator protein-1, interleukin 1beta, tumor necrosis factor-alpha, MMP-1, MMP-3, and MMP-9 were found with crystal abrasion combined with negative pressure. Negative pressure alone resulted in increased gene expression of MMP-1 and MMP-3 but of a quantitatively reduced magnitude when compared with negative pressure with crystal abrasion. LIMITATIONS: It is unclear that molecular changes seen with these treatments can result in clinical effect. CONCLUSION: The abrasive component of microdermabrasion is necessary for stimulating expression of key genes involved in dermal remodeling.

Adult↗
PubMed2006

BRAF and NRAS mutations in melanoma and melanocytic nevi.

In this report, we investigated BRAF/NRAS mutations in samples from a case-control study of melanoma and a series of benign melanocytic nevi. We evaluated potential associations between BRAF mutations and histopathologic and pigmentary characteristics of melanoma. Mutations in BRAF and NRAS were detected by sequencing microdissected/laser-captured DNA from 18 in-situ melanomas, 64 primary melanomas, and 51 nevi. Nevi showed the highest frequency of BRAF mutations (82%). BRAF mutations were identified in 29% of invasive melanomas and in only 5.6% of in-situ melanomas. Mutations in NRAS were found in 5.2% of primary melanomas, 5.9% of nevi and no NRAS mutations were seen in in-situ melanomas. A majority of the BRAF mutations observed in primary invasive melanoma were seen in superficial spreading melanoma (15/17), and melanomas with BRAF mutations were also more likely to be found on a body site that was likely to be exposed to intermittent sun exposure compared with chronic or no sun exposure (P=0.02). Tumors with BRAF mutations were also significantly more likely to occur in association with a contiguous nevus (odds ratio 3.49, 95% confidence interval 1.06-11.46), although a contiguous nevus was not found in all melanomas with a BRAF mutation. Our data support the evidence that the mitogen-activated protein kinase pathway is upregulated in a large percentage of melanocytic lesions, but these mutations are not sufficient for malignant transformation. We suggest that BRAF mutations contribute to benign melanocytic hyperplasia, but are likely to contribute to invasive melanoma only in conjunction with other mutations.

Case-Control Studies↗
PubMed2006

Melanoma.

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Algorithms↗
PubMed2005

Wide excision without radiation for desmoplastic melanoma.

BACKGROUND: Adjuvant radiation has been proposed for the treatment of patients with desmoplastic melanoma, who reportedly have local recurrence rates as high as 40-60%. The authors investigated local recurrence rates at a tertiary referral center to determine the success of wide excision alone for patients with desmoplastic melanoma. METHODS: A review of a prospectively maintained melanoma clinical data base identified 65 patients between March 1997 and March 2004 with pure cutaneous desmoplastic melanoma. Complete surgical, histopathologic, and staging information was collected along with data on outcome, including local, regional, and distant recurrence and survival. RESULTS: Similar to previous reports, patients with desmoplastic melanoma had a male-to-female ratio of 2 to 1, a mean age of 65.0 years (range, 31-92 yrs), and the majority of their tumors (55%) were located on the head and neck. The mean Breslow depth at diagnosis was 4.21 mm, with 38% of tumors thicker than 4.0 mm. All patients in this series underwent wide excision without radiation therapy. Surgical margins < or = 2 cm were obtained for all trunk and extremity lesions and for 63% of head and neck lesions that measured > 1 mm in depth (63%). Margins of 1-2 cm were obtained for the remaining patients. Among 49 patients who had a minimum of 2 years of follow-up (mean, 3.7 yrs), the local recurrence rate was 4% (2 of 49 patients). Seventy-eight percent of the patients studied remained alive with no evidence of disease. CONCLUSIONS: Local recurrence rates in the current series were considerably lower than the historically reported rates. This finding suggests that, for patients with desmoplastic melanoma, wide local excision with careful attention to appropriate margins produces excellent local control rates without the need for adjuvant radiation.

Adult↗
PubMed2005

Dermal matrix remodeling after nonablative laser therapy.

OBJECTIVE: Nonablative laser therapy is widely practiced for cutaneous rejuvenation. We sought to quantify dermal molecular changes after exposure of photodamaged skin to nonablative laser energy. METHODS: Nonablative laser therapy of forearm skin using either a 585-nm wavelength pulsed dye laser or a 1320-nm wavelength neodymium:yttrium-aluminum-garnet laser was performed. Serial biopsy specimens were obtained at baseline and various times after treatment. RESULTS: Statistically significant increases in type I procollagen messenger RNA expression occurred after exposure of photodamaged skin to each laser. Induction was 47% (P < .05) and 84% (P < .05) above baseline levels 1 week after laser therapy among those treated with the pulsed dye and neodymium:yttrium-aluminum-garnet lasers, respectively. Substantial induction of type III procollagen, various matrix metalloproteinases, and primary cytokines was also demonstrated. Responses with respect to all molecules studied were highly variable. LIMITATIONS: This study addresses molecular changes after a single laser exposure whereas clinically, serial treatments are often provided. CONCLUSIONS: Nonablative laser therapy may result in quantifiable alterations in molecules associated with remodeling of the dermal matrix, although responses vary greatly among patients.

Aged↗
PubMed2005

Reliability of sentinel lymph node biopsy for regional staging of head and neck Merkel cell carcinoma.

OBJECTIVE: To determine (1) the reliability of sentinel lymph node (SLN) biopsy and (2) the need for cytokeratin 20 (CK-20) immunostaining in the staging of head and neck Merkel cell carcinoma (MCC). DESIGN: Retrospective cohort study (median follow-up of 34.5 months). SETTING: Tertiary care center. PATIENTS: Ten patients with head and neck MCC who underwent regional staging with SLN biopsy (SLNB) and CK-20 immunostaining. INTERVENTIONS: Sentinel lymph nodes were identified using preoperative lymphoscintigraphy, intraoperative gamma probe, and isosulfan blue dye. The SLNs were evaluated with hematoxylin-eosin and CK-20 immunostaining. Patients with negative SLNB results were followed up clinically. MAIN OUTCOME MEASURES: Percentage of positive SLNs, regional recurrence in the setting of a negative finding from SLNB, and percentage of positive SLNs requiring CK-20 immunostaining for diagnosis of micrometastatic MCC. RESULTS: At least 1 SLN was identified in every patient. Of 24 nodes, 19 (79%) were from the neck region and 5 (21%) were from the parotid basin. Two of the 24 SLNs, in 2 (20%) of 10 patients, were positive for metastatic disease. Both positive SLNs appeared negative on hematoxylin-eosin-stained sections, but small foci of micrometastatic MCC were identified with CK-20 immunostaining. No cranial nerve complications occurred. Regional failure in the setting of a negative finding on SLNB was observed in 1 (12%) of 8 patients. CONCLUSIONS: Biopsy of SLNs represents a safe and reliable technique for regional staging of MCC of the head and neck. It provides pathologists with a limited number of SLNs for focused analysis, which is imperative because hematoxylin-eosin immunostaining is often insufficient for identifying micrometastatic MCC. The use of anti-CK-20 antibody allows accurate identification of micrometastatic MCC.

Aged↗
PubMed2005

Microstaging accuracy after subtotal incisional biopsy of cutaneous melanoma.

BACKGROUND: A significant portion of cutaneous melanoma may remain after subtotal incisional biopsy. The accuracy of microstaging and impact on clinical practice in this scenario are unknown. OBJECTIVE: Our purpose was to examine microstaging accuracy of an initial incisional biopsy with a significant portion of the clinical lesion remaining (> or =50%). METHODS: Patients with cutaneous melanoma, diagnosed by incisional biopsy with > or =50% of the lesion remaining, were prospectively evaluated for microstaging accuracy, comparing initial Breslow depth (BD1) to final depth (BD2) after excision of the residual lesion. Impact on prognosis and treatment was also evaluated. RESULTS: Two hundred fifty of 1783 patients (14%) presented with > or =50% residual clinical lesion after incisional biopsy. The mean BD1 was 0.66 mm; the mean BD2, 1.07 mm (P = .001). After complete excision of the residual lesion, upstaging occurred in 21% and 10% became candidates for sentinel node biopsy. CONCLUSION: An incisional biopsy with > or =50% clinical lesion remaining afterward may be inadequate for accurate microstaging of melanoma. This scenario is relatively uncommon but clinically significant.

Aged↗
PubMed2005

Microdermabrasion: a molecular analysis following a single treatment.

BACKGROUND: Microdermabrasion is a popular method of superficial skin resurfacing. It is unclear if dermal remodeling actually occurs. OBJECTIVE: To rigorously investigate the molecular alterations observed following a single microdermabrasion treatment. METHODS: Forty-nine subjects received a single microdermabrasion treatment to buttock skin. Serial in vivo biochemical and immunohistological analyses were performed. Reverse transcriptase real-time polymerase chain reaction and immunohistochemistry assays were used to evaluate changes in transcription factors (AP-1, NF-kappaB), primary cytokines (interleukin-1beta, tumor necrosis factor-alpha), matrix metalloproteinases (MMP-1, MMP-3, MMP-9), barrier repair enzymes (acetyl-coenzyme A carboxylase, 3-hydroxy-3-methylglutaryl coenzyme A reductase), and type I procollagen. Results Elevation of transcription factors, primary cytokines, and matrix metalloproteinases occurs rapidly after a single microdermabrasion treatment. Two of 11 subjects also demonstrated increased type I procollagen messenger RNA and protein levels 14 days after treatment. No alteration in stratum corneum thickness was detected. CONCLUSION: Microdermabrasion activates a dermal remodeling/wound healing cascade with minimal epidermal disruption. Evidence now exists to further study manipulation of variables such as number and timing of microdermabrasion sessions.

Acetyl-CoA Carboxylase↗