Precursor lesions of melanoma: do they exist?

Increased diagnosis of thin superficial spreading melanomas: A 20-year study

BACKGROUND

Diagnostic practice by dermatopathologists evaluating pigmented lesions may have evolved over time.

OBJECTIVES

We sought to investigate diagnostic drift among a group of dermatopathologists asked to re-evaluate cases initially diagnosed 20 years ago.

METHODS

Twenty nine cases of dysplastic nevi with severe atypia and 11 cases of thin radial growth-phase melanoma from 1988 through 1990 were retrieved from the pathology files of the Massachusetts General Hospital. All dermatopathologists who had rendered an original diagnosis for any of the 40 slides and the current faculty in the Massachusetts General Hospital Dermatopathology Unit were invited to evaluate the slide set in 2008 through 2009.

RESULTS

The mean number of melanoma diagnoses by the 9 study participants was 18, an increase from the original 11 melanoma diagnoses. A majority agreed with the original diagnosis of melanoma in all 11 cases. In contrast, a majority of current raters diagnosed melanoma in 4 of the 29 cases originally reported as dysplastic nevus with severe atypia. Interrater agreement over time was excellent (kappa 0.88) and fair (kappa 0.47) for cases originally diagnosed as melanoma and severely atypical dysplastic nevus, respectively.

LIMITATIONS

The unbalanced composition of the slide set, lack of access to clinical or demographic information, access to only one diagnostic slide, and imposed dichotomous categorization of tumors were limitations.

CONCLUSIONS

A selected cohort of dermatopathologists demonstrated a general trend toward the reclassification of prior nonmalignant diagnoses of severely atypical dysplastic nevi as malignant but did not tend to revise prior diagnoses of cutaneous melanoma as benign.

Conjunctival melanocytic nevi of childhood

Two young patients with conjunctival compound nevi are presented to illustrate two types of abnormalities that lead to difficulty in distinction of these nevi from invasive melanomas. In Case 1, inflammation is associated with disruption of the nevus cell architecture and cytologic atypia. In Case 2, the occurrence of a combined nevus (compound and blue nevus types) in the conjunctiva leads to diagnostic problems. Circumscription of the lesions, lack of mitoses in the substantia propria, and lack of pagetoid spread of atypical cells in the adjacent conjunctival epithelium support benign diagnoses in both cases.

Conjunctival melanoma

Conjunctival melanoma is an uncommon tumor that is likely to recur and carries an overall mortality rate of approximately 30%. The seemingly unpredictable and enigmatic character of this entity has initiated much debate over the past decades regarding the etiology, histogenesis, prognosis, and preferred management. This review outlines the historical perspective; incidence and demographics; etiologic factors; histogenesis; cytogenetic findings; clinical characteristics; histopathologic and ultrastructural features; differential diagnoses; classifications; management of primary, recurrent, and systemic disease; survival after conjunctival melanoma; and diverse factors of potential prognostic significance. Finally, a brief outlook on present and future research objectives is provided.

Probable congenital melanocytic nevus of the oral mucosa: case report

There are few case reports of congenital melanocytic nevi affecting the oral mucosa. We report the clinical and histologic features of an intraoral melanocytic lesion that in our opinion meets the criteria for the diagnosis.