Francisco Ferro de Beça1, Joanne Lopes2, Fernanda Maçoas3, Fátima Carneiro1, José Manuel Lopes4. 1. IPATIMUP, Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal Faculty of Medicine, University of Porto, Porto, Portugal Centro Hospitalar de São João, Porto, Portugal. 2. Centro Hospitalar de São João, Porto, Portugal. 3. Unidade Local de Saúde da Guarda, Guarda, Portugal. 4. IPATIMUP, Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal Faculty of Medicine, University of Porto, Porto, Portugal Centro Hospitalar de São João, Porto, Portugal jmlopes@ipatimup.pt.
Abstract
BACKGROUND: Mesenchymal colorectal polyps are uncommon lesions, particularly those of neurogenic origin. We describe a mucosal Schwann cell hamartoma of the colon with tactoid features, so far reported in peripheral nerve sheath tumours, and address its differential diagnosis and clinical implications. CASE PRESENTATION: A 72-year-old man underwent screening colonoscopy that presented a 5-mm polyp on distal sigmoid. Histologically, it displayed a lesion in the lamina propria comprising oval structures with tactoid features and bland spindle cells, entrapping adjacent crypts. No ganglion cells were seen. Spindle cells expressed only S-100 protein and vimentin. DISCUSSION: Mucosal Schwann cell hamartoma was recently recognized as distinct from common (submucosal) colorectal Schwannomas and so far not associated to inherited syndromes. Thus, it should be considered in the differential diagnosis of look-alike lesions (eg, ganglioneuroma, neuroma, and neurofibroma) that may occur in the setting of inherited syndromes such as Cowden syndrome, multiple endocrine neoplasia-2B, and type 1 neurofibromatosis.
BACKGROUND: Mesenchymal colorectal polyps are uncommon lesions, particularly those of neurogenic origin. We describe a mucosal Schwann cell hamartoma of the colon with tactoid features, so far reported in peripheral nerve sheath tumours, and address its differential diagnosis and clinical implications. CASE PRESENTATION: A 72-year-old man underwent screening colonoscopy that presented a 5-mm polyp on distal sigmoid. Histologically, it displayed a lesion in the lamina propria comprising oval structures with tactoid features and bland spindle cells, entrapping adjacent crypts. No ganglion cells were seen. Spindle cells expressed only S-100 protein and vimentin. DISCUSSION: Mucosal Schwann cell hamartoma was recently recognized as distinct from common (submucosal) colorectal Schwannomas and so far not associated to inherited syndromes. Thus, it should be considered in the differential diagnosis of look-alike lesions (eg, ganglioneuroma, neuroma, and neurofibroma) that may occur in the setting of inherited syndromes such as Cowden syndrome, multiple endocrine neoplasia-2B, and type 1 neurofibromatosis.