Congenital cutaneous Langerhans cell histiocytosis and cutaneous mastocytoma in a child

Langerhans cell histiocytosis and mastocytoma are clonal disorders of bone-marrow-derived cells, most commonly seen in the pediatric age. Infiltration of mast cells and Langerhans cells in the same lesion has been published before, but, to our knowledge, this is the first time that the occurrence of two mastocytomas and Langerhans cell histiocytosis is reported. It could be hypothesized that both clonal disorders of bone-marrow-derived cells could have a common origin

'Rainbow pattern': a dermoscopic sign of invasive melanoma

Background: The 'rainbow pattern' was initially described as a highly specific dermoscopic feature of Kaposi sarcoma. Since then, it has been reported in many benign and malignant cutaneous tumours, including a few malignant melanomas (MMs). Aim: To determine the frequency and presentation of this dermoscopic pattern in primary cutaneous MMs in comparison to other cutaneous tumours. Methods: The presence of a rainbow pattern was evaluated in a sample of 1100 dermoscopic images of different melanocytic and nonmelanocytic cutaneous neoplasms. Results: The rainbow pattern was observed in 23 of 245 (9.4%) MM and 44 of 855 (5.1%) non-MM neoplasms. MMs presenting this feature were generally thicker: 82.6% > 1 mm and 43.0% > 2 mm. Compared with non-MMs, rainbow pattern in MMs was more commonly focal (82.7% vs. 36.4% nonfocal, P = 0.001) and associated with > 2 dermoscopic structures associated with MM (100% vs. 9% with fewer, P = 0.001). Conclusion: The rainbow pattern is a dermoscopic sign that can occasionally be observed in invasive MMs. In MMs, this feature is usually associated with other dermoscopic criteria of MM and located in a focal and eccentric area, as opposed to a diffuse and isolated presentation in non-MM neoplasms