An Isolated Neurofibromal Polyp of the Colon

Abstract

Solitary neurofibromal colonic polyps are a rare entity, particularly outside the setting of neurofibromatosis type 1. The clinical significance of such lesions has not yet been established. Though typically benign tumors, neurofibromas have been reported to undergo malignant transformation, with an increased risk of malignancy when associated with neurofibromatosis. In this case report, we present the rare case of a man found to have an isolated colonic neurofibroma without any personal/family history or clinical features of neurofibromatosis. A 59-year-old man with a history of dyslipidemia and degenerative joint disease presented for a routine screening colonoscopy. The colonoscopy revealed no abnormalities except a 3 mm transverse colon polyp and another 4 mm polyp in the descending colon. Biopsy results showed the descending colonic polyp to be a tubular adenoma; however, multiple levels of the 3 mm transverse colon polyp revealed interlacing bundles of spindle cells extending into the lamina propria with comma-shaped nuclei consistent with findings seen in neurofibroma. Isolated colonic neurofibromas are rare and understudied. While they are usually benign, they may undergo malignant transformation, especially when associated with neurofibromatosis. Thus, patients presenting with isolated neurofibromas should be followed for development of neurofibromatosis and malignancies.

Neurofibroma of the Colon: A Diagnostic Mimicker of Gastrointestinal Stromal Tumor

“…Gastrointestinal involvement has been documented in 25% of patients with NF1, and most of the neurofibromas involve the stomach and small intestine, presenting as ganglioneuromas or neurofibromas [3]. Here we report a rare CD34-positive sporadic colonic neurofibroma, which may be misdiagnosed as GIST.…”

“…However, an accurate diagnosis is clinically important, since it would be an initial manifestation of NF1 in patients without any other clinical manifestations of the disease [3]. In that case, a small but non-negligible potential for malignant transformation exists.…”

“…Schwann cells were discovered to be the cells of origin for neurofibromas, but understanding the more complicated interplay of multiple cell types in tumorigenesis – specifically of recruited heterogeneous cell types such as mast cells and fibroblasts – has important implications for surgical therapy of these tumors [2]. Two of the following diagnostic criteria should be fulfilled to make a diagnosis of NF1: ≥6 café au lait macules; ≥2 neurofibromas of any type or 1 plexiform neurofibroma; freckling in the axillary or inguinal region; optic glioma; ≥2 iris hamartomas (Lisch nodules); bony lesions (pseudoarthrosis); or a 1st-degree relative with NF1 [3, 4]. It is an autosomal dominant disorder; however, sporadic inheritance has been noted as well.…”

“…They are relatively common – particularly at superficial cutaneous sites, where they present as localized, pedunculated growths [7]. In the colon, only 4 cases of sporadic neurofibroma have been reported in the English literature in a patient without NF1 [1, 3, 8, 9]. …”

Rectal Mucosal Schwann-Cell Hamartoma: A Case Report and Literature Review

“…Although there is a proliferation of Schwann cells and S-100 positivity, mucosal Schwann cell hamartomas are different from schwannomas in that they lack Verocay bodies, Antoni A and Antoni B areas, lymphoid infiltrations, and lymphoid cuffs. Neurofibromas and ganglioneuromas can also be distinguished from Mucosal Schwann cell hamartomas on the basis of the presence of fibroblasts with axons and ganglion cells, respectively [1,4,5].…”