An improved approach to diagnosing and treating conjunctival mucoepidermoid carcinoma

Conjunctival 'mucoepidermoid carcinoma' revisited: a revision of terminology, based on morphologic, immunohistochemical and molecular findings of 14 cases, and the 2018 WHO Classification of Tumours of the Eye

In 2018, the consensus meeting for the WHO Classification of Tumours of the Eye decided that conjunctival mucoepidermoid carcinoma should be reclassified as adenosquamous carcinoma, as this represented a better morphological fit. To examine the applicability of this terminology, we studied the clinical, histopathological, immunohistochemical and molecular pathology of 14 cases that were originally diagnosed as conjunctival mucoepidermoid carcinoma. There were 7 (50%) females and 7 (50%) males. The median age was 64 years. The left eye was affected in 8 and the right eye in 6 patients. In-situ carcinoma was present in 11/14 (79%) cases and comprised in-situ squamous cell carcinoma (SCC) and conjunctival intraepithelial neoplasia with mucinous differentiation (CIN-Muc). Invasive carcinoma was present in 11/14 (79%) cases. Group 1 (1/11 cases, 9%) comprised invasive SCC only. Group 2 (6/11 cases, 55%) comprised SCC with mucinous differentiation, manifesting as scattered intracellular mucin, occasionally together with intercellular mucin, with no evidence of true glandular differentiation. Group 3 (3/11 cases. 27%) comprised true adenosquamous carcinoma. Group 4 (1/11 cases, 9%) comprised pure adenocarcinoma. Thirteen of 14 cases (93%) underwent FISH for MAML2 translocation and none were rearranged. Two cases harboured high-risk HPV (type 16 and 18). The combined findings confirm that all lesions in our study were not mucoepidermoid carcinoma, but represented predominantly SCC with mucinous differentiation and adenosquamous carcinoma. We, therefore, recommend future revision of the WHO classification to include SCC with mucinous differentiation alongside adenosquamous carcinoma.

Conjunctival Intraepithelial Neoplasia with Mucoepidermoid Differentiation: A Case Report of a Subtle Lesion

OBJECTIVE

To describe the clinical presentation, diagnostic imaging, and treatment options of conjunctival intraepithelial neoplasia (CIN) with mucoepidermoid differentiation, an in situ stage of mucoepidermoid carcinoma of the conjunctiva (MCC).

RESULTS

We report the case of an 86-year-old man presenting with a subtle limbal lesion that had only mild erythema and elevation. Based on a few atypical clinical features and an abnormal ultrahigh-resolution optical coherence tomography (UHR OCT), an incisional biopsy was performed revealing CIN with mucoepidermoid differentiation. Treatment involved aggressive surgical excision. No evidence of recurrence was noted in the 5 years of follow-up.

CONCLUSION

MCC is an aggressive tumor that has a tendency to be invasive and recur after treatment. Therefore, early diagnosis and treatment is critical. CIN with mucoepidermoid differentiation may represent the earliest stage of MCC. It can present subtly, with a clinical resemblance to benign and less aggressive ocular surface lesions. Imaging with UHR OCT may be helpful to detect early neoplasia. A high level of suspicion must be maintained when evaluating potential ocular surface tumors.

Clinicopathologic and immunohistochemical studies of conjunctival large cell acanthoma, epidermoid dysplasia, and squamous papilloma

PURPOSE

To evaluate clinicopathologically and immunohistochemically a spectrum of conjunctival squamous proliferations.

DESIGN

Retrospective clinicopathologic study.

METHODS

One large cell acanthoma, 7 epidermoid dysplasias, and 4 squamous papillomas were evaluated with microscopy and biomarkers Ki-67, p53, epithelial membrane antigen (EMA), Ber-EP4, AE1, AE3, and 8 individual cytokeratins. Normal associated conjunctiva served as a baseline for interpretation.

RESULTS

The large cell acanthoma recurred 4 times but retained its benign histopathologic features. The cells were 2-3 times larger than the keratinocytes of the normal conjunctiva and did not display atypia. Immunohistochemistry revealed a low Ki-67 proliferation index (PI) in the large cell acanthoma compared with high indices in dysplasias and papillomas. p53 was negative in the nuclei of normal epithelium while positive in all neoplasms, most intensely in the dysplasias. Immunostaining showed similar staining patterns for cytokeratins in large cell acanthoma and normal conjunctiva, except for full-thickness CK14 positivity and CK7 negativity in the lesion. Dysplasias generally lost normal CK7 expression and frequently abnormally expressed CK17. The papillomas displayed a normal cytokeratin pattern but exhibited a higher than normal PI and weak p53 positivity.

CONCLUSIONS

Conjunctival large cell acanthoma is a morphologically distinctive clonal entity with clinical and immunohistochemical phenotypic characteristics denoting a dysplasia of minimal severity. Because of recurrences without invasion, it requires treatment. Dysplasias exhibited more deviant biomarker abnormalities including frequent aberrant full-thickness CK17 positivity and CK7 negativity. The absence of major cytokeratin derangements in the squamous papillomas may be of ancillary diagnostic value for lesions displaying borderline cytologic features.