Nasal polyps, sebaceous cysts, papillomas and other diseases may be caused by a small lump growing in the mouth of the nostril without pain. 1. Nasal polyps:The pathogenesis of nasal polyps is not clear, and it is considered to be caused by a variety of factors such as infection and allergy. Patients will have nasal polyps, nasal congestion, increased secretion, smell disorders and other symptoms, when the polyps grow to the nostrils can appear when the nostril mouth grows a small pimple painless phenomenon. 2. Sebaceous cysts:Sebaceous cysts are caused by the blockage of hair follicles and sebaceous glands, and the main symptoms of patients are cysts, redness, swelling, and fluctuating sensation. As a result, patients will have the symptom of a small lump growing in the mouth of the nostril without pain. 3. Papilloma:The cause of papilloma is not clear, and it is considered to be caused by various factors such as environment, viral infection, inflammation stimulation and so on. The patient’s nasal cavity will appear tumor, so the patient will have a nostril mouth grow a small lump without pain performance. When the patient has the symptom of a small lump in the nostril mouth without pain, he should go to the hospital in time to find out the cause of the disease and follow the doctor’s instructions for treatment.