Dermoscopic presentation of a 2‐mm melanoma in situ

Abstract

A 37-year-old woman first presented in 2003 with an irregularly bordered, slightly elevated, brown-black plaque on her left lower leg and a history of the mole changing over a period of 6 months. Upon excision, the diagnosis of melanoma in the setting of pre-existing naevus, Clark level III, Breslow thickness 0.9 mm, was made. Standard staging work-up disclosed no significant abnormalities. The patient was subsequently managed via 3-monthly clinical surveillance and at the second follow-up visit in April 2004, a new 2-mm light-brown, bluish macule was detected on the left thigh (Fig. 1a). Dermoscopic examination revealed asymmetry of colour and structure, uneven distribution of brownish and bluish irregular streaks and some bluishblack dots with elements of an atypical pigment network (Fig. 1b). The excisional biopsy of this lesion revealed the histopathological features of a melanoma in situ, namely nests of melanocytes with varied size and shape, confluent junctional nest of melanocytes (Fig. 2a) as well as increased numbers of atypical melanocytes at the dermo-epidermal junction and in the upper layers of the epidermis (Fig. 2b).Despite the ABCD rule, a significant proportion of melanomas do not fit the D criterion of 6 mm. 1 In fact small melanomas have a reported frequency of 11.4-38.2% of all diagnosed melanomas. 1-4 In view of a complete skin examination with dermoscopy requiring less than 3 min, 5 we propose all lesions be routinely evaluated under dermoscopy, regardless of the size.Our present observation emphasizes the need for clinicians to be alert to the development of new lesions on individuals with a prior history of melanoma, particularly in the first 6-12 months post excision of the first melanoma. A recent study based in Queensland, Australia, found the risk of a second primary invasive melanoma to be 12.7/1000 person-years in the first 12 months, a figure much higher than that of the general population. 6 Accordingly, we consider our case of an early diagnosis of a second primary melanoma in situ following an invasive melanoma, a product of vigilant surveillance. Provided that the recommendation of close surveillance is adhered to, it is anticipated that any second primary lesion will be smaller and at Correspondence: Professor H Peter Soyer, Figure 1 (a) Clinical photograph of small pigmented macule measuring 2 mm in diameter. (b) Dermoscopy: Asymmetry of colour and structure, with a hint of an atypical pigment network. There is an uneven distribution of brownish and bluish irregular streaks and some bluish-black dots.

A tiny invasive melanoma: a case report with dermatoscopy and dermatopathology

“…One previous study reported that intensity of dark pigmentation was the defining clinical characteristic in each of 13 (including 5 invasive) small melanomas (<4 mm diameter) in a series of 95 melanomas [5], although this may in fact be due to selection bias as minute dark melanomas are more likely to be noticed and assessed in comparison to small pale melanomas which may be present but not detected. The case reported here, unlike the two previously reported smallest in-situ melanomas [7,11] did not exhibit unequivocal dermatoscopic asymmetry, and this is significant because dermatoscopic asymmetry is a generally accepted criterion for all of the published clinical and dermatoscopic algorithms. However in one study of consecutive pigmented skin lesions with a maximum diameter of 6mm (range 3–6 mm) excised in a specialized university dermatology department over four years, 34 out of a total of 103 melanocytic lesions were melanomas [12], and of those 34 melanomas only 11 (32.4%) were asymmetrical.…”

“…It satisfied the criteria for malignancy of the 3-point checklist [8], the Menzies method [9] and Chaos and Clues [10]. Teng et al reported the dermatoscopic features of an in-situ melanoma with a diameter of 2 mm [11]. A published dermatoscopy image revealed unequivocal asymmetry of both color and structure with some lines radial segmental and blue-gray structures.…”

Dermatoscopy of a minute melanoma

“…Previously a melanoma 2 mm in diameter was described by Teng et al 2 That case was similar in that the patient had a previous melanoma and was under careful surveillance. That melanoma was more structurally complex with radial lines (streaks) and reticular lines (atypical pigment network).…”

“…This lesion did not reach the diameter threshold for melanoma of 6 mm according to the ABCD (asymmetry, border irregularity, colour variegation, diameter greater than 6mm) acronym, 1 but it is now known that 11.4 to 38.2% of diagnosed melanomas are less than 6 mm in diameter. 2 Blue or grey structures are a clue to malignancy dermatoscopically because they are found in melanoma, 3 pigmented basal cell carcinoma 4 and pigmented Bowen's disease 5 as well as in some benign conditions including lichen planuslike keratoses (lichenoid keratoses) 6 and pigmented actinic keratoses. 7 Given the small size of the lesion and the scarcity of structures it was not possible to differentiate between these entities with confidence by pattern analysis and the need for a biopsy was recognised.…”

Embryology of a melanoma? A case report with speculation based on dermatoscopic and histologic evidence

“…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].…”