Naevocytic naevi with vascular-like spaces.

Area of Science:

• Dermatopathology
• Histology
• Cell Biology

Background:

• Naevocytic naevi are common benign melanocytic neoplasms.
• The presence of vascular-like spaces within naevi is an uncommon finding.
• Understanding the cellular and structural characteristics of these spaces is crucial for accurate diagnosis.

Purpose of the Study:

• To investigate the histological and immunohistochemical features of naevocytic naevi exhibiting anastomosing lacunae.
• To determine the cellular origin and nature of the cells lining these lacunae.
• To elucidate the potential pathogenetic mechanisms involved in the formation of these vascular-like spaces.

Main Methods:

• Histopathological examination of fourteen naevocytic naevi cases.
• Immunohistochemical staining for vimentin, S100 protein, factor VIII-related antigen, Ulex europaeus I, laminin, and type IV collagen.
• Evaluation of basement membrane components surrounding the lacunae.

Main Results:

• Fourteen cases of naevocytic naevi with anastomosing lacunae resembling vascular spaces were identified.
• Cells lining the lacunae were positive for vimentin and S100 protein, consistent with naevus cells.
• These cells were negative for factor VIII-related antigen and Ulex europaeus I, ruling out endothelial origin.
• Absence of laminin and type IV collagen surrounding the lacunae indicated basement membrane abnormalities.

Conclusions:

• The cells lining the lacunae are indeed naevus cells, not endothelial cells.
• The formation of vascular-like spaces in these naevi is likely attributed to defective basement membrane production or increased degradation.
• This defect leads to a lack of cellular cohesion, resulting in the observed lacunar spaces.