Abstract
A dermatopathologist can only make a specific diagnosis based on the presence of defined histologic criteria. Most cases encountered in routine practice show enough criteria on standard examination to reach an unequivocal diagnosis. Sometimes further steps must be taken, such as cutting deeper levels or using special stains, to clarify uncertainties. Occasionally the final histologic diagnosis must remain uncertain or borderline. This most frequently occurs in the assessment of melanocytic lesions. There is no single diagnostic criterion for the histologic diagnosis of melanoma. “Criteria are evaluated differently by different observers. They are derived from typical, not difficult cases, and are seldom tested. In sum, none of the criteria useful for the diagnosis of melanoma are specific and diagnostic . . .” [1]. A series of architectural and cytological criteria are listed (Table 1) [2] and these criteria would apply to the majority of melanomas encountered in routine dermatopathology practice, but the quantity or quality required to make a diagnosis are not defined. It is accepted that melanomas, as with all malignant tumours, evolve over time and the rate of growth has been measured in one study [3]. Currently, few very small melanomas are diagnosed [4,5]. The increased use of dermatoscopy and digital monitoring should lead to more small melanomas being encountered [6]. What is not known is how commonly these very small melanomas, at the ‘infantile’ stage of Ackerman’s analogy, lack sufficient criteria to make the diagnosis of melanoma. It seems reasonable to speculate that such lesions exist. This leads us to pose the question, “Can melanomas be diagnosed earlier by adding information from history and dermatoscopy to the findings at histopathology?” and we present the case that led us to consider these matters. TABLE 1 Histologic criteria for the diagnosis of malignant melanoma (after Ackerman) (Table 32.4, Weedon’s Skin Pathology[2].)
Highlights
A dermatopathologist can only make a specific diagnosis based on the presence of defined histologic criteria
What is not known is how commonly these very small melanomas, at the ‘infantile’ stage of Ackerman’s analogy, lack sufficient criteria to make the diagnosis of melanoma
The pathologist did agree that there were certain apparent inconsistencies with the alternative diagnosis of nevus: 1. A new junctional nevus is uncommon on the central part of the face at mature age. (Personal observation by author DW.) 2. It is seen occasionally, extension down a follicle is uncommon in a non-congenital-type nevus. (Personal observation by author DW.) a diagnosis of “atypical nevus” was issued and this was confirmed by another senior pathologist at the same institution
Summary
A dermatopathologist can only make a specific diagnosis based on the presence of defined histologic criteria. Most cases encountered in routine practice show enough criteria on standard examination to reach an unequivocal diagnosis. The final histologic diagnosis must remain uncertain or borderline. This most frequently occurs in the assessment of melanocytic lesions. None of the criteria useful for the diagnosis of melanoma are specific and diagnostic . A series of architectural and cytological criteria are listed (Table 1) [2] and these criteria would apply to the majority of melanomas encountered in routine dermatopathology practice, but the quantity or quality required to make a diagnosis are not defined. The increased use of dermatoscopy and digital monitoring should lead to Observation | Dermatol Pract Concept 2012;2(4):
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