Schwannomatosis-NEC (Not Elsewhere Classified) ‚ Principles for Diagnosis and Routines for Follow Up - Tumor

Department of Translational Medicine - Hand Surgery, Lund University, Malmö, Sweden

A right-handed, 53-year-old male nurse, with a long history and treatment of venous vascular malformations in right hand/forearm, was referred 2021 because of a tumour in the superficial radial nerve in the left forearm (lately increased in size). A Schwannoma (MRI supported diagnosis) was excised (diagnosis confirmed by PAD). In 2022, the patient was diagnosed for another Schwannoma (dorsal part of calf; sural nerve; MRI supported and fine needle biopsy); Schwannoma excised early 2023 without any local complications. Later, he developed a pulmonary embolus (anticoagulant six months; without residual problems).

At an MRI routine follow up (no symptoms), one suspected Schwannoma found in right trigeminal nerve, one intraspinal/intra-/extraforaminal located C1-C2 level/C2 nerve root and one intraspinal C5 level (no symptoms; neurosurgeon consulted; no action). During spring 2024, discomfort right thigh, where MRI showed in total five nerve tumours (size maximum 37 mm) in the sciatic, obturator, femoral and undefined nerves. A whole sequence genetic panel analysis related to Schwannomatosis 3.0 did not reveal any genetic mutations (like in SMARCB1, SMARCE1, LZTR1, NF1, NF2, PRKAR1A, SUFU or DGCR8 genes). A follow up MRI of brain and spinal cord shows no change; presently followed by neurologist.

In conclusion, a 53-year-old male with long-standing vascular malformations in the right hand/forearm, with two excised Schwannoma (contralateral forearm and calf), five suspected Schwannoma in the thighs, one in trigeminal nerve and two at cervical spinal nerve levels, where no genetic mutations were found. Discussion about diagnosis and definitions (Schwannomatosis-NEC = not elsewhere classified) and guidelines for follow up are appreciated.

Weisman et al, Am J Med Genet. 2023;191A:2467-2481

Plotkin et al, Genet Med. 2022 24(9):1967-1977