Our patient is a 51-year-old female. Two years ago, she presented with minor abdominal discomfort and dyspepsia for one month. Endoscopy revealed that hundreds of nodules, ranging from 2 mm to 5 mm in diameter, protruded from mucosa in her whole esophagus and intestine. No ulcer or other abnormal manifestations could be observed. Biopsies were taken from different sites. Laboratory analysis indicated a slightly high IgG level of 25.9 g/L (normal 8.0–17.0 g/L), IgA level of 4.46 g/L (normal 0.72–4.29 g/L) and a slightly low complement C3 level of 0.73 g/L (normal 0.79–1.52 g/L), complement C4 level of 0.14 g/L (normal 0.16–0.38 g/L), and normal ranges for CEA (1.17 ng/ml, normal 0.00–5.00 ng/ml) and AFP (1.40 ng/ml, normal 0.00–8.10 ng/ml). Qualitative check of Bence-Jones protein was negative in urine. The suspected clinical diagnosis was primary systemic amyloidosis, and whether it is a hereditary disease should be differentiated. Her parents and younger sister were all given endoscopy examinations following the patient, but no similar nodules were found in them. Biopsy tissues from esophagus, terminal ileum, cecum, colon and rectum were submitted for pathological examination. The histopathological characteristics of each specimen were similar. The mucosa was unremarkable, epithelial cells demonstrated bland nuclei, with no atypia or mitotic activity. And no lymphoid inflammatory infiltration in the stroma was observed. In submucosa, there were several small round nodules which were well circumscribed and unencapsulated. The nodules were predominantly composed of collagen bundles, and a variable number of stellate tumor cells located within the collagen. The collagen were hyalinized and no skeinoid fibers could be observed. The tumor cells were haphazard and not arranged in storiform or palisading pattern. In most nodules, they located peripherally; but in a few nodules, they located diffusely. In all of the lesions, inflammatory cells, calcification, mitoses and necrosis were absent. Immunohistochemically, the neoplastic cells showed strong cytoplasmic vimentin staining, absent h-CALD, CD34, desmin, CD163, AE1/AE3, CK7 and CK20 staining. The proliferation rate, measured by detection of ki-67 antigen expression, was very low (approximately positive in 1% tumor cells). Histochemically, the lesions were blue with Masson Trichrome stain, red with periodic acid Schiff (PAS) stain, and pink with Congo red stain. Based on these features, the pathological diagnosis was eruptive collagenoma. After diagnosis, the patient was given some medicines of proton pump inhibitors and modulating intestinal flora for her symptoms, and no specific treatment was given for collagenoma. One month later, all of the discomfort disappeared. After that, she had a routine endoscopy examination once in 6 months. As of September 2016, no obvious progress was observed.