Correlation of dermoscopic structures on mucosal sites
Studies about correlation between dermoscopy and histology of mucosal lesions are scarce. In addition, the histological diagnosis of melanocytic lesions in mucosal sites can be challenging since benign and malignant lesions can present with atypical findings (Yélamos et al., 2016). The pigment network is usually absent in mucosal lesions, due to the nearly complete absence of rete ridges. However, with the exception of the pigment network, melanocytic lesions of the mucosa can present with dermoscopic structures similar to those seen in non-mucosal locations such as lines, dots/globules, circles and structureless areas.
Multiple patterns can be observed in benign melanocytic lesions of mucosae.
The homogenous pattern
is composed of structureless brown areas on dermoscopy. Histologically, it reveals flattened rete ridges along with acanthosis (Lin et al., 2009).
The ring-like pattern
presents with pigmented circles, and the fish scale-like pattern shows half circles. They both share the same histopathological correlations revealing hyperpigmented rete ridges with skip areas of pigmentation at the top of the dermal papillae (Ferrari et al., 2014; Lin et al., 2009).
The parallel pattern
is composed of brown, linear parallel streaks (Ferrari et al., 2014) and the hyphal pattern consists of lines resembling fungal hyphae. Histologically, they corresponds to hyperpigmentation at the tip of the obliquely elongated rete ridge (Lin et al., 2009).
The dotted-globular pattern
presents with multiple dots/globules with similar sizes and shapes and corresponds to locally aggregated melanin in the upper dermis (Lin et al., 2009).
A multicomponent pattern
consisting of blue, gray and white colors, regression structures, blue-whitish veil and structureless areas can be seen in mucosal melanomas (Blum et al., 2011; Lin et al., 2009). Histologically, the correlation is similar to that described in non-mucosal locations.
