An atypical presentation of a rare lesion.

Conjunctival stromal tumour (COST) is a rare lesion first described in 2012.1Herwig MC Wells JR Grossniklaus HE. Conjunctival stromal tumor: report of 4 cases.Ophthalmology. 2012; 119: 682-687Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar The literature describes a lesion that grows over several years with various appearances but a common histology.1Herwig MC Wells JR Grossniklaus HE. Conjunctival stromal tumor: report of 4 cases.Ophthalmology. 2012; 119: 682-687Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar, 2Lam J Ang A Vermeulen T Ardakani NM. Conjunctival stromal tumor: report of 2 new cases and review of the literature.Int J Surg Pathol. 2021; 29: 337-342Crossref PubMed Scopus (4) Google Scholar, 3El-Khoury J Marchand M Allaire G Robert MC. Conjunctival stromal tumour: case report and review of the literature.Can J Ophthalmol. 2020; 55: e174-e175Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar We report a conjunctival lesion that met the histopathologic diagnostic criteria for COST. It developed in an anophthalmic eye within 4 weeks of enucleation for aggressive thyroid eye disease that had manifested with proptosis, chemosis, and corneal perforation. The lesion was atypical in how fast it developed and thus emphasizes the reactive nature of COST. A 61-year-old male with no previous ocular history presented with a 2-month history of pain and redness in the right eye. He had an extensive atherosclerotic history including several coronary artery bypass grafts and had long been a heavy smoker. Examination of the right eye showed conjunctival injection with mild chemosis, 2 mm lagophthalmos, and minimal proptosis. The patient's vision was reduced in the right eye, though he did have a dense cataract. He did not have a relative afferent pupillary defect. The left eye showed only mild conjunctival injection. The patient was begun on intensive lubrication and sent for imaging and blood work, which confirmed the working diagnosis of thyroid eye disease (TED). Review 2 weeks later showed worsening proptosis and chemosis with eyelid swelling, and intravenous steroids were begun. The symptoms continued to worsen over the next few days despite treatment resulting in significant proptosis, exposure keratopathy, and corneal perforation. The patient was referred to a tertiary centre for urgent right-sided orbital decompression and corneal grafting. At the start of the procedure, the contents of the eye self-expressed, and the operation was subsequently converted to an evisceration. At 4-week follow-up, a large conjunctival lesion measuring 35 × 12 × 5 mm had developed and was protruding between the lids. It was smooth and pink in appearance with a fleshy/rubbery texture. Imaging was performed, and an urgent biopsy was arranged. Histopathologic examination of the excised conjunctival tissue showed a loose stroma that was partly due to edema of the substantia propria. The latter contained evenly distributed cytologically bland cells with spindle, ovoid, and stellate morphology, between which were wiry collagen fibres. Occasional scattered multinucleated stromal cells were present. Scattered mast cells also were seen. Occasional mixed inflammatory cells featuring small lymphocytes, some eosinophils, neutrophils, and plasma cells were present. At higher power, quite a few of the spindle and avoid cells exhibited pseudonuclear inclusions (Fig. 1A). Immunohistochemistry showed that the spindle cells were CD34 positive (Fig. 1B), and some of the more stellate cells showed factor XIIIa positivity. The cells were negative for smooth muscle actin and S100. The constellation of morphologic and immunohistochemical features was entirely consistent with a conjunctival stromal tumour. COST was first described in 2012 by Herwig et al.,1Herwig MC Wells JR Grossniklaus HE. Conjunctival stromal tumor: report of 4 cases.Ophthalmology. 2012; 119: 682-687Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar with only a few cases reported since then. It is a rare benign lesion, thought to be reactive, that typically grows slowly over a period of several years on the ocular surface, though it also has been reported on the palpebral conjunctiva.4Park JY Lee SW Hwang JH Kim HJ Choi J. Palpebral conjunctival and tarsal stromal tumor.Korean J Ophthalmol. 2019; 33: 97-98Crossref PubMed Google Scholar The appearances reported have varied from cystic and nodular to fibrovascular in nature, with colours varying from red to pink to white. It can be diffuse or localized. The key to the diagnosis of COST is the histologic features, typically consisting of spindle-shaped cells with pseudonuclear inclusions and multinucleated cells. Histology is positive for CD34, factor XIIIa, vimentin, and in part CD68.1Herwig MC Wells JR Grossniklaus HE. Conjunctival stromal tumor: report of 4 cases.Ophthalmology. 2012; 119: 682-687Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar, 2Lam J Ang A Vermeulen T Ardakani NM. Conjunctival stromal tumor: report of 2 new cases and review of the literature.Int J Surg Pathol. 2021; 29: 337-342Crossref PubMed Scopus (4) Google Scholar, 3El-Khoury J Marchand M Allaire G Robert MC. Conjunctival stromal tumour: case report and review of the literature.Can J Ophthalmol. 2020; 55: e174-e175Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar It is important to identify these key immunohistochemistry markers to differentiate COST from conjunctival myxoma, which has had histologic and clinical similarities described.5Qin XY Jin ZH Wang YP Zhang ZD. Conjunctival myxoid stromal tumour: a distinctive clinicopathological and immunohistochemical study.Br J Ophthalmol. 2019; 103: 1259-1265Crossref PubMed Scopus (12) Google Scholar Conjunctival myxoma is an important differential diagnosis because it can be associated with life-threatening conditions.1Herwig MC Wells JR Grossniklaus HE. Conjunctival stromal tumor: report of 4 cases.Ophthalmology. 2012; 119: 682-687Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar,3El-Khoury J Marchand M Allaire G Robert MC. Conjunctival stromal tumour: case report and review of the literature.Can J Ophthalmol. 2020; 55: e174-e175Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar Several factors have been proposed to contribute to the pathogenesis of COST, such as blepharitis and possible factors in the tear film. It is thought that an inflammatory pathogenesis or a reactive process1Herwig MC Wells JR Grossniklaus HE. Conjunctival stromal tumor: report of 4 cases.Ophthalmology. 2012; 119: 682-687Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar is possible for a typically slow-growing lesion. The patient we report here had an acute onset with a significant lesion size. Our patient raises the question of whether there may have been any additional factors that contributed or even triggered the unusually rapid development of COST in this patient. The underlying aggressive TED would most certainly have been a source of inflammation, but we note that the histology contained mixed inflammatory cells and was not rich in plasma cells. As such, these histology findings do not support TED being the underlying cause or at least not the sole cause. This then points us toward the surgical intervention as possibly playing a significant role. The evisceration surgery would have caused an abundance of inflammation or even played a reactive role. The histology reviewed would be supportive of this underlying cause as having a role in triggering the pathology. The case described here is different from others described. The lesion was of significant size, being large enough to protrude between the eyelids. It also developed rapidly in a patient following evisceration secondary to acute TED, raising the possibility of newly proposed triggers to the pathogenesis. The case that we report is an unusual presentation of a rare lesion that helps contribute to the growing picture of COST. The authors have no proprietary or commercial interest in any materials discussed in this article.