Solitary fibrous tumor of the lacrimal sac mimicking lacrimal sac mucocele: A case report with review of literature

Introduction

Solitary Fibrous Tumor (SFT) was described as a primary spindle cell tumor of the pleura.1 It is diagnosed in different parts of the body including viscera of the abdomen, pelvis and trunk. Six percentages of all SFTs arise in the head and neck region.2 SFT of the lacrimal sac is rare, very few cases of SFT have been reported worldwide. Because of its varied clinical presentations and histopathologic appearances, it can be misdiagnosed. We present a rare case of SFT of the lacrimal sac which presented like lacrimal sac mucocoele with review of literature.

Case Presentation

A 67 year old man, presented with history of watering and discharge in the right eye for 2 years, associated with painless progressive swelling in the medial canthus. He has a history of ruptured abscess treated from elsewhere 2 months back. His best corrected visual acuity (BCVA) was 6/12 in both eyes. External examination showed a firm, well-circumscribed, non-tender mass of size 13*10 mm in right lacrimal sac region, not extending above medial canthal tendon (Figure 1). There was no regurgitation of mucopurulent discharge or pus on applying pressure over lacrimal sac area. Anterior segment examination revealed immature cataracts in both the eyes while posterior segment examination was unremarkable. Obstruction in the lacrimal passage was confirmed by probing and syringing. He was clinically diagnosed as chronic dacryocystitis with lacrimal sac mucocele and was posted for dacryocystorhinostomy (DCR). During DCR, after skin incision and blunt dissection, there was a yellowish mass with vascularisation on the surface. The mass was removed in-toto and specimen sent for histopatological examination, after explaining to the patient and the bystanders. Haemostasis was achieved and wound closed in layers.

Histopathological examination revealed structures of lacrimal sac tissue with subepithelial circumscribed tumor tissue formed by plump to spindle cells arranged in perivascular pattern with extensive stromal fibrosis. There were numerous stag horn vessels with epitheloid cell proliferation. Interspersed mitosis, pseudovascular spaces lined by epitheloid cells and giant cells seen (Figure 2A,B). Immunohistochemisty showed diffuse and strong positivity for CD34, Bcl2, vimentin and CD99 (Figure 3 A,B,C, and D), suggestive of solitary fibrous tumor, intermediate grade.

Patient was followed up for 6 months without recurrence. The study adhered to the ethical principles outlined in the Declaration of Helsinki. A written informed consent was taken from the patient about the use of clinical data and clinical photographs for the purpose of the study.

Discussion

Solitary fibrous tumors are composed of spindle-shaped cells and were originally considered a neoplasia of the mesothelium. It was first described in 1931 by Klemperer and Rabin as a distinct mesothelial tumor arising from the pleura and mediastinum.3 Many cases have been described other sites like subcutaneous tissues, paranasal sinuses, nasal cavity, meninges, extremities, thoracic wall, and abdomen (liver, adrenal, peritoneum, urogenital system). 4 Earlier, some such tumours may probably have been described as hemangiopericytoma. SFT of the orbit is rare and typically present as benign orbital masses in middle-aged adults.

Lacrimal sac SFTs may present as nasolacrimal duct obstruction, recurrent dacryocystitis, or as a slow-growing mass in the medial canthal region. Lacrimal sac SFT is extremely rare and only around 15 cases were reported in literature in English language (Table 1). Most of these cases were presented as mass in the medial canthal area and epiphora as the presenting complaint. 4 cases had a previous history of DCR.5, 6, 7, 8 They may easily be misdiagnosed due to their rarity, heterogeneity of clinical presentations and histological appearances.9 Definitive diagnosis can be made by histopathological and immunohistochemical examination only, due to the variability in radiological appearances. 10

Microscopically, SFTs consists of ovoid to spindle cells that are haphazardly arranged with varying cellular densities in admixture with stromal collagen bundles.11 SFTs can be a mimicker of other tumours such as mesotheliomas and sarcomas .Hence immunochemical staining has proven useful in establishing the diagnosis.12 The tumour stains positively for CD-34, CD-99, BCL-2 antigens and vimentin and negatively for S-100 protein, desmin, cytokeratin and actin.13 Less than 15% of solitary fibrous tumours are aggressive. Malignancy is evidenced by hypercellularity, cytologic atypia, necrosis, infiltrative margins, and high mitoses. 14 Such features were not present in this case.

Solitary fibrous tumours are chemo-resistant, total excision is the preferred treatment. In cases of partial resection, local recurrence or malignant transformation may occur. 5  As there is a high chance of recurrence, complete surgical excision and continued follow-up should be emphasized. 10

Figure 1

Clinical picture showing mass in the medial canthal area

Figure 2

Histopathological examination of lacrimal gland tumor section (H and E section,revealed structures of lacrimal sac tissue with subepithelial circumscribed tumor tissue forme by plump to spindle cells arranged in perivascular pattern (arrow marks) with extensive stromal fibrosis.

Figure 3

Immunohistochemistry of lacrimal sac tumor showing strongly positive for A: CD-34 cells, B: Bcl2, C: Valentin and D: CD99, suggestive of solitary fibrous tumor

Conclusion

The lacrimal sac SFT can present as nasolacrimal duct obstruction, recurrent dacryocystitis, or slow-growing mass in the sac area. Even though lacrimal sac SFT is very rare, it should be considered as a differential diagnosis of medial canthal region mass in patients with epiphora.

Conflict of Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Source of Funding

None.