Determinants of BRAF mutations in primary melanomas

The RAS/mitogen-activated protein kinase pathway sends external growth-promoting signals to the nucleus. BRAF, a critical serine/threonine kinase in this pathway, is frequently activated by somatic mutation in melanoma. Using a cohort of 115 patients with primary invasive melanomas, we show that BRAF mutations are statistically significantly more common in melanomas occurring on skin subject to intermittent sun exposure than elsewhere (23 of 43 patients; P<.001, two-sided Fisher's exact test). By contrast, BRAF mutations in melanomas on chronically sun-damaged skin (1 of 12 patients) and melanomas on skin relatively or completely unexposed to sun, such as palms, soles, subungual sites (6 of 39 patients), and mucosal membranes (2 of 21 patients) are rare. We found no association of mutation status with clinical outcome or with the presence of an associated melanocytic nevus. The mutated BRAF allele was frequently found at an elevated copy number, implicating BRAF as one of the factors driving selection for the frequent copy number increases of chromosome 7q in melanoma. In summary, the uneven distribution of BRAF mutations strongly suggests distinct genetic pathways leading to melanoma. The high mutation frequency in melanomas arising on intermittently sun-exposed skin suggests a complex causative role of such exposure that mandates further evaluation.     

Expression of melanocyte differentiation antigens and ki-67 in nodal nevi and comparison of ki-67 expression with metastatic melanoma

Nodal nevi represent a potential diagnostic pitfall in the analysis of lymph nodes. They may be confused with metastatic melanoma or carcinoma. Although several morphologic guidelines exist for the recognition of nodal nevi, on occasion immunohistochemical studies may be helpful for diagnosis, especially when melanocytes extend into the lymph node parenchyma. To learn more about the immunohistochemical profile of nodal nevi we examined 15 nodal nevi for the expression of S-100 protein, gp100 (HMB-45), Melan-A/MART-1 (A103), and tyrosinase (T311), and we studied the expression of Ki-67 (MIB-1) in nodal nevi and 40 melanoma metastases (35 lymph node and five cutaneous metastases). All nodal nevi were homogeneously immunoreactive for S-100 protein, tyrosinase, and Melan-A/MART-1. Two nodal nevi were focally positive for gp100. Fourteen of 15 nodal nevi were completely negative for Ki-67. One large cellular nodal nevus showed nuclear labeling in <0.2% of melanocytes. All metastases showed MIB-1 labeling. However, the percentage of labeled tumor cells varied widely, ranging from 2% to 80%. These results demonstrate that MIB-1 and HMB-45 are helpful reagents for the distinction of nodal nevi from melanoma. Immunohistochemistry for S-100 protein, Melan-A/MART-1, or tyrosinase facilitates the recognition of melanocytes but does not distinguish between nodal nevus and metastatic melanoma.     

Evolving phenotype of Marfan's syndrome

AIM: To examine evolution of the physical characteristics of Marfan's syndrome throughout childhood. METHODS: 40 children were ascertained during the development of a regional register for Marfan's syndrome. Evolution of the clinical characteristics was determined by repeat evaluation of 10 patients with sporadic Marfan's syndrome and 30 with a family history of the condition. DNA marker studies were used to facilitate diagnosis in those with the familial condition. RESULTS: Musculoskeletal features predominated and evolved throughout childhood. Gene tracking enabled early diagnosis in children with familial Marfan's syndrome. CONCLUSIONS: These observations may aid the clinical diagnosis of Marfan's syndrome in childhood, especially in those with the sporadic condition. Gene tracking has a role in the early diagnosis of familial Marfan's syndrome, allowing appropriate follow up and preventive care.     

Ultrasonographic evaluation of breech presentation as a risk factor for hip dysplasia

In order to gain more information of breech position as a risk factor for congenital hip dysplasia or dislocation, the hips of 408 newborns delivered in the breech position were examined by ultrasound. Clinical examination was performed by both experienced paediatricians and orthopaedic surgeons. The infants were re-examined by ultrasound at 2–3 months of age. Twenty-five newborns (6.1%) had neonatal hip instability. Breech presentation as a risk factor was confirmed, with first borns, breech position with extended knees, and high birthweight as special high-risk groups. Ultrasound showed subluxation in most of the unstable hips. The main benefit of using ultrasound was that direct visualization permitted more reliable evaluation, especially when the clinical findings were uncertain. Normal ultrasound findings in false positive and uncertain Ortolani tests reduced the frequency of unnecessary treatment. Because ultrasound was used in follow-up, the need of radiography was reduced. There were no late-detected cases of hip dysplasia or dislocation, indicating that routine follow-up is not necessary in breech infants with normal hips at birth, provided that the neonatal screening is optimal.     

Hepatic artery pseudoaneurysm: diagnosis with real-time and pulsed Doppler US

Duplex ultrasonography (US), consisting of real-time and pulsed Doppler US, was used to identify a pseudoaneurysm in a patient with recurrent bleeding and chronic pancreatitis. The authors present a case that illustrates the limitations of real-time US in evaluating sonolucent masses in pancreatitis and the need for using pulsed Doppler technique.     

Desmoplastic Melanoma: A Pathologically and Clinically Distinct Form of Cutaneous Melanoma

Background Desmoplastic melanoma (DM) is a rare variant characterized by the presence of fusiform melanocytes in a sclerotic stroma. Pathologic heterogeneity within DM may account for the controversy regarding the clinical presentation and prognosis of DM compared with conventional melanoma (CM).Methods We identified 131 patients with a diagnosis of DM seen between 1979 and 2002. Tumors were categorized as either pure DM (pDM; n = 92), if desmoplasia was prominent throughout the entire invasive tumor, or mixed DM (mDM; n = 39), if fibrosis was well developed in only parts of an otherwise non-DM. Differences in clinical behavior among pDM, mDM, and CM (n = 3976) were examined.Results Seventy-three percent of patients with DM had tumors >2 mm in depth, compared with 31% of patients with CM (P < .001). Regional nodal metastasis was uncommon in patients who presented with clinically localized pDM (1%) compared with those with mDM (10%) or CM (6%) (P < .05, pDM vs. CM). Five-year melanoma-specific mortality was lower for patients who presented with pDM compared with mDM (11% vs. 31%; P < .01). Patients with pDM and CM had a similar melanoma-specific mortality despite a 3-fold difference in median tumor depth (3.6 vs. 1.2 mm, respectively).Conclusions DMs can be divided into two subtypes based on a histological quantification of desmoplasia. Tumors with prominent fibrosis (pure subtype) are unlikely to disseminate to regional lymph nodes and are associated with a favorable outcome when compared with those with mixed desmoplasia or CM.     

Immunohistochemical analysis of novel monoclonal antibody PNL2 and comparison with other melanocyte differentiation markers

PNL2 is a novel monoclonal antibody, which has recently been introduced as an immunohistochemical reagent to stain melanocyte and tumors derived thereof. In the present study, we analyzed the immunoreactivity of this mAb in various normal tissues, melanocytic nevi, primary and metastatic melanoma, nonmelanocytic tumors, including histologic mimickers of melanoma as well as angiomyolipoma, and multiple cell lines derived from different tumors types. We used several tissue microarray panels as well as selected conventional sections from tissue blocks. For metastatic melanoma, immunoreactivity for PNL2 was compared with A103 (Melan-A/MART-1), T311 (tyrosinase), HMB45 (gp100), and D5 (MITF). Positive staining with PNL2 was found in normal melanocytes and neutrophils, but no other normal cell type. Among melanocytic lesions, both benign nevi as well as primary malignant melanomas, especially epithelioid variants thereof, were commonly immunopositive. Only 1 of 13 desmoplastic melanomas reacted with PNL2. PNL2 showed high sensitivity for metastatic melanoma (87%). In comparison, 82% of metastatic melanomas were positive for A103, 76% for HMB45, 92% for T311, and 84% for D5. The combined use of all five reagents minimized the number of immunonegative cases. None of the selected nonmelanocytic tumors (carcinomas or soft tissue neoplasms) was positive for PNL2 in this series except for angiomyolipomas and chronic myeloid leukemias and 1 single case of a malignant peripheral nerve sheath tumor with heterologous differentiation (malignant Triton tumor). Despite its reactivity with neutrophils, PNL2 appears to be a valuable supplementary reagent for the diagnosis of melanocytic tumors.