Myxoma is a benign soft tissue tumor that presumably derives from primitive mesenchyme. It is characterized histopathologically by abundant mucoid material, a loose meshwork of reticulin fibers, and relatively small numbers of spindle- and stellate-shaped cells.1 The stromal matrix is rich in glucosaminoglycans and hyaluronic acid, and it is sparse in collagen and vascular structures.1 Myxoma can appear as localized disease or as a component of Carney complex, which includes cutaneous and cardiac myxomas, multiple pigmented lesions, and endocrine overactivity, leading to significant morbidity and mortality.2 Myxoma is the most common primary cardiac tumor. This tumor can arise in the skeletal muscle, bone, skin, genitourinary system, gastrointestinal tract, and nasal sinuses.3 It can rarely involve ocular structures and has been recognized in the eyelid, orbit, and conjunctiva.4- 6
In a review of 2455 conjunctival lesions submitted to an ophthalmic pathology laboratory, only 4 patients (0.002%) were found to have conjunctival myxoma.4 In a clinical review of 1643 patients with conjunctival lesions, myxoma was found in 1 case (<0.001%).5 Because of its rarity, conjunctival myxoma can simulate other conjunctival tumors, such as amelanotic nevus, amelanotic melanoma, squamous cell carcinoma, lipoma, and cyst.6 We describe a 31-year-old African American man who had a yellow, translucent subconjunctival mass that proved to be a conjunctival myxoma on histopathological examination.
A 31-year-old African American man had a 2-year history of conjunctival swelling in his left eye. The lesion was diagnosed as a conjunctival cyst, and drainage was attempted. Eighteen months later, the swelling worsened and a solid conjunctival mass was noted, prompting referral to the Oncology Service, Wills Eye Hospital, Philadelphia, Pa. The patient had no history of ocular trauma and was otherwise healthy.
The visual acuity was 20/20 OU. The right eye was normal. External examination of the left eye disclosed a well-circumscribed, yellow-pink, translucent mass on the nasal bulbar conjunctiva (Figure 1). The mass had 2 parts, including a solid basal part measuring 12 × 11 × 6 mm and a cystic apical part measuring 5 × 5 × 2 mm. The clinical differential diagnosis included amelanotic nevus, amelanotic melanoma, myxoma, fibrous histiocytoma, and lipoma. The lesion was excised using the previously described no-touch technique.7
Anterior segment of the left eye showing a well-circumscribed, yellow-pink, translucent mass with a solid basal part and a cystic apical part on the nasal bulbar conjunctiva.
Histopathological examination revealed a lesion composed of loose, myxoid areas that alternated with areas of spindle and stellate cells, which was consistent with benign conjunctival myxoma (Figure 2). Both cellular groups had moderately large hyperchromatic and slightly pleomorphic nuclei and were embedded in a loose mucoid stroma. The stroma contained reticulin fibers, sparse small blood vessels, and collagen fibers (Figure 2). Some of the tumor cells had clear, circular, intranuclear inclusions, and some contained clear cytoplasmic vacuoles. Numerous mast cells were scattered throughout the myxoid stroma (Figure 3).
Conjunctival myxoma. The hypocellular stroma contains delicate collagen fibers (hematoxylin-eosin, original magnification ×50) (A) and abundant mucoid material confirmed by intense positive staining with Alcian blue (original magnification ×20) (B).
Hypocellular myxoma contains multinucleated spindle cells with intranuclear vacuoles. Arrow indicates mast cell (hematoxylin-eosin, original magnification ×250).
Systemic evaluations of the patient for cardiac, endocrine, and cutaneous abnormalities including echocardiography and levels of thyroid-stimulating hormone, growth hormone, and adrenocorticotropic hormone were negative. After 11 years of follow-up, the patient remained healthy without recurrence of the conjunctival mass or evidence of a systemic abnormality.
Myxoma rarely occurs in the conjunctiva. To our knowledge, only 22 well-documented cases of conjunctival myxoma have been published in the English literature (Table).8- 21 The tumor usually occurs in adults and is uncommon in children. The mean age of the 22 published cases was 48 years (median age, 50 years; age range, 18-80 years), and 2 patients (9%) were younger than 20 years.8- 21 Both sexes were affected equally.8- 21 Similarly, a review of 58 patients who all had soft tissue myxomas revealed a mean age of 55 years, with only 1 patient (2%) younger than 20 years.3
Conjunctival myxoma is typically seen as a well-circumscribed, yellow-pink, translucent, cystic and/or solid mass.8- 21 Of the 22 reported cases, the conjunctival mass was described as well-circumscribed in 20 cases (91%) and diffuse in 2 cases (9%).8- 21 The color of the conjunctival mass, when mentioned, was yellow in 9 cases (50%), pink in 8 cases (44%), and white in 1 case (6%).8- 21 The conjunctival lesion was translucent in 14 cases (64%) and solid in 8 cases (36%).8- 21
Conjunctival myxoma has characteristic histopathological features.11,13,14 It consists of scattered, relatively small numbers of stellate- and spindle-shaped cells disposed in a mucinous matrix with delicate reticulin fibers, sparse vascular structures, and mature collagen fibers.11,13,14 The mucinous matrix is composed predominantly of hyaluronic acid, with a lesser amount of chondroitin sulfate. Ultrastructurally, myxoma cells have intracytoplasmic vacuoles and cytoplasmic filaments arranged in loose, wavy bundles.11,13,14 These vacuoles are consisted with dilated rough endoplasmic reticulum. It seems that the mucoid matrix and extracellular fibrils are produced by myxoma cells. There are also intranuclear vacuoles that are consistent with invaginations of markedly folded nuclear membrane. Immunohistochemical studies13,14,17,21 showed myxoma cells were immunoreactive for vimentin and α smooth muscle actin but negative for S-100 protein, desmin, and myoglobulin.
Conjunctival myxoma differs clinically and histopathologically from myxomas of extraocular soft tissues in some aspects. Unlike extraocular soft tissue myxomas, conjunctival myxoma often contains cyst-like cavities. The latter were noted in 9 of the 22 published cases.8- 21 In our case, the patient was diagnosed as having a conjunctival cyst, and drainage was attempted before referral to our service. Additionally, on histopathological examination, mast cells can be observed in conjunctival myxoma.11,13,14
The differential diagnosis of conjunctival myxoma includes nevus, amelanotic melanoma, fibrous histiocytoma, cyst, lymphangioma, myxoid neurofibroma, spindle cell lipoma, rhabdomyosarcoma, and myxoid liposarcoma.6 Unlike conjunctival amelanotic nevus and melanoma, myxoma does not have prominent intrinsic vascularity or pigmentation.6 Myxoid neurofibroma can have a similar clinical picture. It contains cells with spindle-shaped nuclei with thick, wavy bundles of collagen and can be associated with systemic neurofibromatosis.11 Both fibrous histiocytoma and myxoma stain positively with Alcian blue, which is abolished by pretreatment with hyaluronidase. Unlike fibrous histiocytoma, myxoma does not show vascularity or significant nuclear pleomorphism.1
The preferred management of conjunctival myxoma is complete excisional biopsy. Of the 22 published cases with conjunctival myxoma, no recurrence or malignant transformation after excisional biopsy of the lesion was observed.8- 21 In a review of 58 patients with myxomas of the soft tissue, only 2 (3%) had recurrence after 8 to 10 months following excision. These 2 patients underwent reexcision, and both were free of recurrent tumor after a mean of 5 years. Recurrence of myxoma can be related to inadequate excision, multicentricity of the tumor, the presence of genetic predisposition, or malignant transformation. In a review of 107 cardiac myxomas submitted to a pathology laboratory, atypical cells simulating malignancy were observed in only 3%.22
Myxomas can be a component of Carney complex, Mazabraud syndrome (bone fibrous dysplasia and intramuscular myxoma), and McCune-Albright syndrome (café au lait spots and multinodular goiter). Carney complex is an autosomal dominant syndrome that includes 2 or more of the following conditions: multiple foci of mucocutaneous pigmentation (face, trunk, lips, conjunctiva), cardiac and extracardiac (skin, breast) myxomas, endocrine overactivity (including Cushing syndrome), pituitary adenoma, unusual testicular tumors, and psammomatous melanotic schwannoma.23 Patients with myxoma, mucocutaneous pigmentation, and/or a family history of Carney complex should undergo a systemic evaluation including echocardiography, computed tomography or magnetic resonance imaging of the body, testicular ultrasound, analysis of the thyroid-stimulating hormone level, adrenocorticotropic hormone level, and growth hormone level, and genetic analysis (PRKAR1A gene at chromosome 17q2).23 Ophthalmic manifestations of Carney complex include facial and eyelid lentigines, pigmentation on the caruncle or conjunctival semilunar fold, and eyelid myxoma.23,24 Kennedy et al15 described a patient with Carney complex who had a myxoma of the palpebral conjunctiva and an additional lesion on his eyelid margin. None of the 22 published cases of conjunctival myxoma in the literature were associated with Mazabraud or McCune-Albright syndromes.8- 21
In summary, conjunctival myxoma can appear as a well-circumscribed, translucent, yellow-pink conjunctival mass in middle-aged patients. Management is generally complete surgical resection.
Correspondence: Dr C. L. Shields, Oncology Service, Wills Eye Hospital, 840 Walnut St, Philadelphia, PA 19107 (email@example.com).
Financial Disclosure: None.
Funding/Support: This work was supported by the Macula Foundation, New York, NY (Dr C. L. Shields), the Eye Tumor Research Foundation, Philadelphia, Pa (Dr C. L. Shields), the Noel T. and Sara L. Simmonds Endowment for Ophthalmic Pathology, Wills Eye Hospital, Philadelphia (Dr Eagle), and the Paul Kayser International Award of Merit in Retina Research, Houston, Tex (Dr J. A. Shields).
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