• Vol. 50 No. 11, 868–870
  • 29 November 2021

A rapidly enlarging left medial orbital lesion

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A 49-year-old man presented with a 2-month history of a rapidly enlarging left medial orbital mass. There was no local inflammation, pain, discharge, visual or nasal symptoms. On examination, there was a firm mass bulging between the left nasal bone medially and the left eye measuring 2x1cm in dimension (Fig. 1), with no overlying skin paresthesia or cervical lymphadenopathy. No punctum was seen. Nasoendoscopy was normal. There was no ophthalmoplegia or exophthalmos on clinical examination.

Computed tomography (CT) of the face showed a rim-enhancing, hypodense ovoid lesion at the medial aspect of the left orbital rim. Magnetic resonance imaging (MRI) scan showed a mass measuring 1.2×1.1×1.4cm. It demonstrated intermediate T1-weighted and intermediate-to-high T2-weighted signal, with prominent peripheral enhancement (Fig. 2). The mass appeared separate from the left nasolacrimal duct sac. The nasal bone left globe and extraocular muscles were intact.

Fig. 1. Clinical photo of the left medial canthal lesion measuring 1.5×1.2cm.

Fig. 2. (A) Axial T2-weighted magnetic resonance imaging (MRI) scan showing intermediate-to-high T2-weighted signal not involving the nasal cavity or the orbit, lying separate from the nasolacrimal duct. (B) Coronal T1-weighted MRI scan with contrast, showing an ovoid superficial lesion at the left nasal bridge with prominent peripheral enhancement, and an intact nasal bone.

Fine needle aspiration cytology (FNAC) showed loosely cohesive polygonal spindle cells. Nuclei were bland, often elongated and wavy/buckled in appearance. No high-grade nuclear features were seen.

What is your diagnosis?
A. Lipoma
B. Nodular fasciitis
C. Solitary fibrous tumour
D. Inflammatory pseudotumour
(non-specific orbital inflammation)
E. Benign peripheral nerve sheath tumour

Findings and diagnosis. The patient underwent surgical excision via a lynch incision, and a fibrous tumour measuring 1.5×1.2cm was resected. It was attached to the medial canthal tendon but not invading the underlying bone. The lacrimal sac was not involved.

Histopathological examination showed fascicles of spindle cells in a fibrous stroma exhibiting focal myxoid change with no significant cytologic atypia. Mitoses were noted but no atypical mitoses were seen. Extravasated red blood cells were seen in the stroma. Immunohistochemical studies showed reactivity for smooth muscle actin and negative staining for desmin, CD34, HMB45, S100 protein and pancytokeratin AE1/AE3, in keeping with nodular fasciitis (Fig. 3). Although not done in our patient, when dedicated FNAC sampling with adequate cell block tissue is available, it is possible to obtain a definite diagnosis with molecular testing for USP6 gene rearrangements in an appropriate cytomorphological context.

Fig. 3. (A) Loosely dispersed bland plump spindle cells on Papanicolaou stain, 400x magnification. (B) Intersecting fascicles of bland plump spindle cells with extravasated red blood cells and scattered mitoses (arrows), 200x magnification. (C) Spindle tumour cells with positive cytoplasmic immunostaining for smooth muscle actin, 400x magnification.

While a specific FNAC-based diagnosis of nodular fasciitis is challenging, recent advancements have shown that cell block ancillary testing for USP6 gene rearrangement may be considered for confirmation of nodular fasciitis.6 These were first identified in aneurysmal bone cysts, and recently in nodular fasciitis, myositis ossificans and cellular fibrous tumours of tendon sheath. It suggests a benign and self-limiting condition, hence the final specific diagnosis has to be interpreted in appropriate clinical and cytomorphological contexts. To note, other conditions associated with USP6 gene rearrangements are very rarely described in the head and neck region.

Local excision of the nodular fasciitis is often performed as the disease can be completely resected, after which local recurrence is rare. Conservative management with observation is a possibility, and some cases have been known to resolve spontaneously.7 Some studies suggest the use of intralesional steroid injections or laser therapy, which may be useful as alternative treatments in areas where complete excision is difficult, or in aesthetically prominent areas such as the face.8 Recurrent masses are so uncommon that malignancies should be considered with careful reassessment of the original diagnosis.9 Our patient has been followed up for 1 year with no recurrence of the lesion. He has no epiphora and the incision has healed well.

Nodular fasciitis is an uncommon but possible differential for a subcutaneous periorbital lesion. The correct diagnosis helps in avoiding overtreatment of these lesions.

Answer: B

REFERENCES

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