Peripheral nerve tumours are relatively common and often pose important diagnostic problems. The present review makes a comparative study of lesions with similar names or morphological characteristics, highlighting the most significant findings. In this first part, the following diagnoses are considered: Conventional soft tissue schwannoma vs. intraneural neurofibroma; plexiform neurofibroma vs. plexiform schwannoma; cellular schwannoma vs. malignant peripheral neural sheath tumour (MPNST); MPNST vs. melanoma; and MPNST vs. monophasic synovial sarcoma.