Solitary fibrous tumors (SFTs) are rare, benign, mesenchymal neoplasms typically involving the pleura, although meningeal, oral, pericardial, kidney, and liver involvement has also been reported. SFT of the orbit is extremely rare and that of eyelids is even rarer with very few reported cases in the literature.[2,3] These tumors typically present with painless and progressive proptosis, palpable lid mass, epiphora, etc. On magnetic resonance imaging (MRI), the tumor appears isointense on T1-weighted images and iso- to hyperintense on T2-weighted images. Usually, SFTs run a nonaggressive course; however, recurrences, tissue invasion, and/or metastasis are rare and mostly seen due to the incomplete resection. On histopathology, the features of SFTs often overlap with that of other spindle cell tumors, especially hemangiopericytoma, and therefore, immunohistochemistry plays an important role in correctly identifying the type of tumor. Characteristically, they show positivity for CD34, vimentin, bcl-2, and STAT6 and negative for desmin, cytokeratin, and S-100. Whereas CD34 is fairly sensitive for SFTs, staining for STAT6 shows both high sensitivity and specificity. Therefore, STAT6 has become an important adjunct with CD34 to help differentiate SFT from other histologic variants. We here report a rare presentation of SFTs with predominant eyelid involvement and multiple recurrences.
A 60-year-old female presented with a painless progressive swelling of the left lower lid for the past 7 years with epiphora. She had similar swelling in the left lower lid in 2006 and 2013, for which she has undergone surgery, although it reappears 1–2 years later. There were no records available pertaining to previous surgical interventions. On examination, a firm diffuse left lower lid mass measuring approximately 20 mm across with poorly defined posterior extent and mild medial ectropion was present [Figure 1a]. On lid eversion, conjunctival scarring with the obliteration of fornix medially and punctal stenosis could be seen. MRI orbit showed a well-defined soft-tissue mass (25 mm × 20 mm × 10 mm TD × AP × CC) appearing isointense on T1W and hyperintense on T2W sequence encroaching into the extraconal space with the indentation on the anteroinferior globe; furthermore, nasolacrimal duct seems to be obliterated [Figure 2a,b]. A total tumor excision through a conjunctival approach was carried out, and a well-defined mass measuring 25 mm × 15 mm adherent to the overlying conjunctiva was identified and retrieved ensuring complete excision [Figure 1b]. The patient recovered well with only mild medial ectropion of the lower lid remaining [Figure 1c].
Histological evaluation revealed a partially capsulated tissue with oval-to-spindle cells arranged in a fascicular and storiform pattern. Tumor also showed epitheloid and hemangiopericytomatous morphology at places; however, no mitosis or necrosis was seen [Figure 2c,d]. On immunohistochemistry, cells were found positive for CD34 and negative for S-100 [Figure 2e].
The patient showed no sign of recurrence at the 6-month follow-up with a partial improvement in epiphora.
SFTs are rare and slow-growing benign mesenchymal tumors consisting of spindle cells. They most commonly arise from the pleura, but extrapleural involvement has also been frequently seen; however, their orbital occurrence is extremely rare and that of eyelids is even rarer.[1,2,3] Although the typical presentation is usually during middle age, the diagnosis should be considered in all age groups. On radiological evaluation, they show isointensity on T1-weighted and heterogenous isointensity to hyperintensity on T2-weighted scans. However, none of these characteristics are diagnostic of SFT, and therefore it may sometimes be difficult to distinguish it from other orbital lesions. Histologically, SFTs display variable morphological patterns that overlap with other spindle cell tumors such as hemangiopericytoma, angiofibromas, and schwanommas. Additional workup with immunohistochemistry is therefore essential to determine the type of spindle cell tumor. SFTs show a strong reactivity to CD34, STAT6, vimentin, and bcl-2; however, they are negative for desmin, S-100, and muscle-specific actin. Although CD34 positivity of SFTs is highly sensitive, it is relatively nonspecific while STAT6 has high sensitivity and specificity. Mostly, SFTs run a benign course, but incomplete resection often leads to recurrences and tissue invasion, and therefore a meticulous tumor excision is imperative. Complete tumor resection rather than histological appearance is the single most important prognostic factor.
In our case, the patient presented with a long-standing eyelid swelling with multiple recurrences following surgical excision. This is an uncommon presentation as eyelid SFTs have rarely been reported and that too with multiple recurrences. We, therefore, emphasize the importance of complete tumor resection and the establishment of accurate diagnosis using appropriate immunohistochemical stains for fibrous tumors. Equally, critical is to keep a long follow-up of such cases as SFTs are known to have malignant transformation.
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A written informed consent (including the images) has been obtained from the patient. All procedures were carried out in adherence to the tenets of the Declaration of Helsinki.
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