Nuchal fibroma

Signs and symptoms

These lesions are generally asymptomatic, although patients give a long history of a solitary, superficial mass. The mass is usually in the neck (hence the name "nuchal-type"), but it can be seen in the extremities, lumbosacral area, buttocks, and face. There is a strong association with diabetes mellitus and Gardner syndrome; in fact, it may be the initial manifestation of Gardner syndrome.

Pathology

The tumors are unencapsulated and poorly circumscribed, showing a firm, white cut surface. Most tumors are about 3.5 cm, but can be up to 8 cm. By microscopic examination, there are haphazardly arranged thick collagen fibers, with a low cellularity and no pleomorphism. There are usually entrapped fat cells, skeletal muscle, and peripheral nerves. The may be perineural fibrosis. The elastic fibers may be altered, which is why an elastofibroma is considered in the differential diagnosis.

Immunohistochemistry

The tumor cells are strongly positive for vimentin, CD34, and sometimes with CD99. There is often (up to 2/3rds) a nuclear reaction with β-catenin.

Diagnosis

Differential diagnoses

The differential diagnosis includes elastofibroma, fibrolipoma, desmoid-type fibromatoses, and nuchal fibrocartilaginous pseudotumor.

Management

Simple excision is curative. However, in patients with Gardner syndrome, up to 45% will develop desmoid-type fibromatosis at other sites, and so this should be searched for and excluded. Patients can develop a recurrence, so follow-up is required.

Epidemiology

This is a rare tumor, presenting over a wide age range, but usually in the third to fifth decades of life. There is a slight male predilection, although this is not seen in syndrome-associated patients. The most common site is the posterior neck, but may also be seen in other sites (extremities, lumbosacral area, buttocks, face).

References

References

1. (1999). "Nuchal-type fibroma". Cancer.
2. (2000). "Nuchal fibroma: A clinicopathological review". The Annals of Otology, Rhinology, and Laryngology.
3. (April 2021). "The 2020 WHO Classification of Soft Tissue Tumours: news and perspectives". Pathologica.
4. (1995). "Nuchal fibroma. A clinicopathological study of nine cases". The American Journal of Surgical Pathology.
5. (2000). "Nuchal fibroma should be recognized as a new extracolonic manifestation of Gardner-variant familial adenomatous polyposis". The Australian and New Zealand Journal of Surgery.