Prospective study of pigmented lesions managed by shave excision with no deep margin transection of melanomas

Melanoma diagnosis at a specialist dermatology practice without the use of photographic surveillance

BACKGROUND/OBJECTIVE

Photographic aides are increasingly used in melanoma surveillance. We report melanoma characteristics detected using traditional surveillance without photographic technologies.

METHODS

Retrospective study of melanomas diagnosed by three dermatologists at a private dermatology practice over 7 years. Patients underwent full skin examinations with dermoscopy and suspect lesions were excised or biopsied. Total body photography (TBP) and serial digital dermoscopic imaging (SDDI) were not used. Patient demographics, melanoma subtype and thickness, location, biopsy technique and keratinocyte cancers diagnosed at the same visit were recorded. Ratio of in situ to invasive melanomas was calculated. Melanoma risk factors were recorded for 69 randomly-selected patients.

RESULTS

492 patients were diagnosed with 615 melanomas during 579 visits. 505 (82%) were in situ (in situ to invasive ratio of 4.6:1). Of the invasive melanomas, 85.5% had a Breslow thickness <0.8 mm, 10 (9.1%) 0.8-1 mm and 6 (5.5%) >1 mm. 43.3% of in situ melanomas were lentiginous or lentigo maligna and 41.6% were superficial spreading melanomas (SSM). Of invasive melanomas, 24.3% were lentigo maligna melanoma and 59.5% were SSM. 48.4% of melanomas were diagnosed by shave procedures. Where risk factors were known, 25% were very-high-risk and 43% had a history of melanoma. Keratinocyte carcinoma was diagnosed by biopsy at 26.1% of visits. Studies using TBP and/or SDDI report in situ to invasive ratios of 0.59:1 to 2.17:1.

CONCLUSION

Tradiational melanoma surveillance with immediate biopsy of suspect lesions results in high in situ to invasive ratios. Studies using photographic surveillance show lower ratios of in situ to invasive disease.

The impact of incomplete clinical information and initial biopsy technique on the histopathological diagnosis of cutaneous melanoma

BACKGROUND/OBJECTIVES

Increased rates of histopathological misdiagnosis of melanoma have been associated with incisional punch more so than shave biopsy when compared with complete excisional biopsy. It is unknown how the increasing utilisation of shave biopsy may impact melanoma diagnosis. The extent to which the provision of clinical information to the pathologist may improve diagnostic accuracy remains unclear. This study assessed the impact of both initial biopsy technique and provision of adequate clinical information to pathologists on the accuracy of histopathological diagnosis of melanoma and disease progression.

METHODS

We conducted a retrospective cohort with nested case-control study of all histopathological false-negative and false-positive melanoma diagnoses from January 2014 to May 2019 from the Victorian Melanoma Service electronic database. Cases were assessed for the initial biopsy type, provision of clinical information on pathology request forms and disease progression associated with false-negative diagnosis.

RESULTS

Partial shave biopsy had higher odds of false-negative (OR 5.19, 95% CI 2.89-9.32; P < 0.001) and false-positive diagnoses (OR 1.95, 95% CI 1.45-2.63; P < 0.001) of melanoma when compared with elliptical excisional biopsy. These odds ratios were comparable with those found with incisional punch biopsy. Providing the suspected clinical diagnosis to pathologists also reduced the odds of false-negative diagnosis with melanoma progression by 3.8-fold (P = 0.02).

CONCLUSION

The choice of initial biopsy technique and providing the suspected clinical diagnosis to pathologists are important for correct histopathological diagnosis of cutaneous melanoma and prevention of further disease progression.