Metastatic malignant melanoma of the leg from a warty acral amelanotic malignant melanoma

European Journal of Dermatology. Volume 11, Number 6, 591-2, November - December 2001, Votre diagnostic !

Author(s) : A. VIRGILI, M. CORAZZA, Dipartimento Medicina Clinica e Sperimentale, Sezione Dermatologia, Università di Ferrara, via Savonarola 9, 44100 Ferrara, Italy.

Summary : A 71-year-old woman presented with an asymptomatic, enlarging, bluish-purple, ecchimotic, oedematous area she had had for two months on her left leg. This dermatitis completely covered all the two lower thirds of her leg. At the same time groups of sparse warty or smooth red-wine papules were observed on the skin, especially on the medial malleolus (Fig. 1). No other cutaneous or mucosal lesion was observed except for a risen wart-like lesion she had had for 7 years on the plantar side of her left foot. It felt hard on palpation and showed a hyperkeratotic cauliflower-greyish surface with haemorragic pin point areas (Fig. 2). In spite of numerous applications of cryotherapy she referred having had in the past and a surgical excision (without histological investigation), the formation had progressively enlarged until it had reached the present 3 cm diameter. A punch biopsy specimen of a papule of the leg (Fig. 3) and successively of the warty plantar lesion (Fig. 4) were performed.

ARTICLE

A 71-year-old woman presented with an asymptomatic, enlarging, bluish-purple, ecchimotic, oedematous area she had had for two months on her left leg. This dermatitis completely covered all the two lower thirds of her leg. At the same time groups of sparse warty or smooth red-wine papules were observed on the skin, especially on the medial malleolus (Fig. 1).

No other cutaneous or mucosal lesion was observed except for a risen wart-like lesion she had had for 7 years on the plantar side of her left foot. It felt hard on palpation and showed a hyperkeratotic cauliflower-greyish surface with haemorragic pin point areas (Fig. 2). In spite of numerous applications of cryotherapy she referred having had in the past and a surgical excision (without histological investigation), the formation had progressively enlarged until it had reached the present 3 cm diameter. A punch biopsy specimen of a papule of the leg (Fig. 3) and successively of the warty plantar lesion (Fig. 4) were performed.

What is your diagnosis?

Histological examination

The biopsy specimen showed epithelioid globose cells of malignant melanoma infiltrating the dermis and focally the hypodermis. The epidermis was completely spared and there was no inflammatory infiltrate.

A neoplastic vasal invasion was also found.

These findings suggested a histological diagnosis of metastatic malignant melanoma. Histopathology of the warty plantar lesion, successively performed, confirmed it was an acral lentiginous melanoma (ALM).

Discussion

About 5% of melanomas are represented by primary pedal melanomas [1], but in Blacks and Orientals the incidence rises to about two thirds of all melanomas [1-4].

Amelanotic melanoma accounts for 2-3% of all malignant melanoma [4].

In a recent statistical survey of melanomas of the foot, Katz [2] observed acral lentiginous melanoma (ALM) in 88.3% of the cases; the remaining part of his series of melanomas of the foot were nodular, superficial spreading melanoma and metastatic melanomas. He observed that all the 11 cases of amelanotic melanomas were ALM. About 80% of the melanoma of the foot were in patients of 57 to 80 years of age. The average age of the amelanotic melanoma subgroup was 77.3 years.

The clinical aspect of ALM can be an eroded nodule of the plantar surface of the foot [5] or mimic plantar warts or subungueal warts [6]. Even if these lesions are amelanotic, a pigmented edge can be observed around the neoformation [7, 8]. This is a very useful diagnostic sign. Recently a case-control study evidenced that patients with melanoma of the foot had a worse 5 - and 10 - year survival rate than patients affected by melanoma of the leg (74.3% and 63.3% for foot lesions vs 85.2% and 77.2% for leg lesions) [9].

The amelanotic ALM have a poorer prognosis than other melanomas. This may be caused by the difficulty and delay in diagnosis [4] due to its amelanotic aspect rather than to a more aggressive biological behaviour.

In our case the ALM of the foot had been masked by numerous inappropriate treatments. It was possible to complete true diagnosis only when we realized that the plantar wart was an ALM and what had seemed a Kaposi's sarcoma of the leg was a pigmented metastatic lesion involving most of the leg.

References

1. Clark WH, Elder DE, Van Horn M. The biologic forms of malignant melanoma. Hum Pathol 1986; 17: 443-50.

2. Katz RD, Potter GK, Slutskiy PZ, Smith RR, Pfau RG, Berlin SJ. A statistical survey of melanomas of the foot. J Am Acad Dermatol 1993; 28: 1008-11.

3. Halder RM, Bridgeman-Shah S. Skin cancer in African-Americans. Cancer 1995; 75: 667-73.

4. Zellman GL. Amelanotic melanoma in black man. J Am Acad Dermatol 1997; 37: 665-6.

5. Southerland CC, Wasserman LM, Ostapehuk AP. Clinical presentation of peduncolated amelanotic melanoma: plantar aspect. J Foot Surg 1991; 30: 72-9.

6. McBurney EI, Herron CB. Melamoma mimicking plantar wart. J Am Acad Dermatol 1979; 1: 144-6.

7. Paladugu RR, Winberg CD, Yonemoto RH. Acral lentiginous melanoma. Cancer 1983; 52: 161-8.

8. Coleman III WP, Loria PR, Reed RJ, Kremens ET. Acral lentiginous melanoma. Arch Dermatol 1980; 116: 773-6.

9. Talley LI, Soong S, Harrison RA, McCarthy WH, Urist MM, Balch CM. Clinical outcomes of localized melanoma of the foot: a case-control study. J Clin Epidemiol 1998; 51: 853-7.


		Figure 1. Clinical appearance of the leg mimicking a Kaposi's sarcoma.


		Figure 2. Flesh-colored plantar verrucous lesion.


		Figure 3. Histological examination of a papule of the leg (HE, original magnification: x 60).


		Figure 4. Histological appearance of the warty acral lesion (HE, original magnification: x 100).