26276 “Google investigates” sudden onset of skin darkening leading to the detection of a gastrointestinal cancer

Abstract

We present a case of a 57-year-old woman who reported a 1-month history of darkening and thickening of the skin overlying her neck, axillae, abdomen, groin, and inframammary areas. She had explored her symptoms online and recognized that this could be indicative of an underlying malignancy. She reported intentional weight loss of 13 kg following a new diet regime, but did not complain of any other systemic gastrointestinal symptoms, such as loss of appetite, alteration in bowel habits, or rectal bleeding. On examination, she had symmetrically distributed, ill defined, velvet-textured hyperpigmented plaques over the axillae, posterior neck, groin and inframammary areas. She also had hyperpigmented patches over the sides of the face. Abdominal examination revealed a firm epigastric mass. In view of the clinical findings in keeping with acanthosis nigricans and the epigastric mass, a gastroscopy was performed which showed a suspicious gastric mass. Biopsy confirmed the presence of a gastric adenocarcinoma, and further imaging revealed metastatic spread to the lymph nodes. She was therefore started on palliative chemotherapy. Malignant acanthosis nigricans (AN) is a rare cutaneous paraneoplastic manifestation, most commonly associated with adenocarcinoma of the gastrointestinal tract. In contrast to the benign form with its insidious onset, malignant AN appears suddenly and is widespread. This case highlights that acute onset acanthosis nigricans may be the only presenting symptom of internal malignancy, and although rare, should be kept in mind. It is particularly unusual in the manner by which the patient self-diagnosed her paraneoplastic phenomenon online.