Related Experiment Video
Updated: Jul 9, 2026

Combining Reflectance Confocal Microscopy with Optical Coherence Tomography for Noninvasive Diagnosis of Skin Cancers via Image Acquisition
Published on: August 18, 2022
Azo pigments and a basal cell carcinoma at the thumb
Eva Engel1, Heidi Ulrich, Rudolf Vasold
1Department of Dermatology, University of Regensburg, Regensburg, Germany.
Abstract:
Basal cell carcinoma is the most common malignant neoplasm of the skin, whereas the localization at the nail unit is very rare. We report the case of a 58-year-old patient with a periungual basal cell carcinoma at the thumb. The specific feature of the reported case is the frequent exposure to fishing baits that the patient had stained with an unknown colorant. The use of chromatography, mass spectrometry and infrared spectroscopy revealed the colorant as the azo pigment Solvent Red 8. Solvent Red 8 is a widespread synthetic azo pigment that is applied to stain consumer products. Compounds such as Solvent Red 8 can be cleaved to carcinogenic amines under, for example, light exposure, in particular after incorporation into the human body. As a result of the frequent skin contact to this azo pigment, this hazard compound might have induced the basal cell carcinoma in our patient.
Related Concept Videos
Skin Cancer
Basal Cell Carcinoma (BCC): BCC is the most common type of skin cancer, accounting for about 80% of cases. It typically develops in...
Pigmentation
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
Skin Diseases and Disorders
Gram-positive Staphylococcus spp. and Streptococcus spp. are responsible for many of the most common skin infections. However, many...
Papillary Dermis
The dermis might be considered the "core" of the integumentary system, as distinct from the epidermis and hypodermis. It contains blood and lymph vessels, nerves, and other structures, such as hair follicles and sweat glands. The dermis is made of two layers of connective tissue that comprise an interconnected mesh of elastin and collagenous fibers, produced by fibroblasts.
Papillary Layer
The papillary layer is made of loose, areolar connective tissue, which means the collagen and...
Changes in Skin Color: Clinical Perspectives
Albinism
Albinism is a genetic disorder that affects (completely or partially) the coloring of skin, hair, and eyes. The defect is primarily...
