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Lymphatic invasion is independently prognostic of metastasis in primary cutaneous melanoma

PURPOSE

Lymphatic invasion (LI) in primary cutaneous melanomas was recently found to be common. In this study, we evaluated LI as an independent prognostic factor.

EXPERIMENTAL DESIGN

This study included 251 patients with vertical growth phase (VGP) primary cutaneous melanomas who had paraffin-fixed lesional tissue and were in a prospective cohort seen between 1972 and 1991, had no clinical evidence of regional nodal disease at diagnosis, and had at least ten years of follow-up. Dual immunohistochemical staining was used to detect lymphatic endothelium (podoplanin) and melanoma cells (S-100). Multivariate logistic regression for ten-year metastasis was used to define independent prognostic factors, and a prognostic tree was developed to characterize and discriminate risk groups. Kaplan-Meier disease-free survival curves for those with and without LI within current American Joint Committee on Cancer stages were compared using the log-rank statistic.

RESULTS

LI was observed in 43% (108 of 251) of the study melanomas. The multivariate model for ten-year metastasis identified four independent prognostic factors: tumor thickness, mitotic rate, LI, and anatomic site. The prognostic tree identified a group of patients with thin (≤1 mm thick) melanomas and poor prognosis: stage IB melanomas with LI. Survival curves for time to first metastasis showed significantly poorer prognosis for patients with LI compared with those without it for both stages IB and IIA.

CONCLUSIONS

LI is common across the range of tumor thicknesses in primary VGP melanomas. It is an independent prognostic factor and significantly increases the risk of metastasis in patients in clinical stages IB and IIA.

Anaesthesia and aspiration pneumonitis

Aspiration pneumonitis describes the inflammatory reaction of the lung parenchyma following contamination by stomach contents. It is an uncommon but potentially lethal complication of general anaesthesia. Protection of the airway from contamination has long been one of the fundamentals of safe anaesthetic practice. Aspiration pneumonitis was first recorded by John Snow in 1858 but not scientifically described until 1946 by Curtis Mendelson, an American obstetrician, who differentiated between the airway obstruction due to inhalation of solid material and aspiration of liquids which resulted in an intense inflammatory reaction of the lung tissue manifesting as bronchospasm, pulmonary oedema and hypoxia. He identified general anaesthesia as a major contributory factor due to the loss of protective airway reflexes and as a result of related animal studies suggested that the aspiration of acidic material resulted in severe pulmonary impairment.

A microstructural model for the anisotropic drained stiffness of articular cartilage

A constitutive model for articular cartilage is developed to study directional load sharing within the soft biological tissue. Cartilage is idealized as a composite structure whose static mechanical response is dominated by distortion of a sparse fibrous network and by changes in fixed charge density. These histological features of living cartilage are represented in a microstructural analog of the tissue, linking the directionality of mechanical stiffness to the orientation of microstructure. The discretized 'model tissue' is used to define a stiffness tensor relating drained stress and strain over a regime of large deformation. The primary goal of this work was to develop a methodology permitting more complete treatment of anisotropy in the stiffness of cartilage. The results demonstrate that simple oriented microscopic behaviors can combine to produce complicated larger scale response. For the illustrative example of a homogeneous specimen subjected to confined compression, the model predicts a nonlinear anisotropic drained response, with inherent uncertainty at cellular size scales.