A 17-year-old adolescent girl presents for treatment of a lesion on her index finger. She reports that the lesion was present for approximately 2 years. Initially, it grew quickly, but recently, it has remained stable in size. A friend told her that it was a wart and she could have it frozen. The patient denies any pain, itching, or bleeding from the lesion. She denies having any other similar lesions elsewhere. Physical examination reveals a light pink, 3-mm, well-circumscribed dome-shaped nodule on the right index finger over the proximal interphalangeal joint. There is no associated erythema or tenderness.
A 74-year-old man presents for his biannual skin examination. After questioning him regarding any new or changing lesions, the clinician learns that he had a new pink growth that appeared on his left elbow 2 weeks earlier. The patient denies having any pain from the lesion, although he noted that it bled a lot when it got caught on his clothing. The patient has a history of extensive actinic damage, as well as a history of a basal cell carcinoma on his chin. Physical examination of the left elbow reveals a firm, rubbery, pink papule with a small black crust at the lateral margin.
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Spitz nevus is a benign melanocytic nevus named after the pathologist Sophie Spitz, who first described this lesion in 1948. Spitz nevi, although inherently benign, may mimic malignant melanomas both clinically and histologically. For this reason, Spitz nevi are often referred to as benign juvenile melanoma. More concerning, however, is that there have been cases of atypical Spitz nevi that have metastasized and caused death.1 This has caused tremendous confusion among researchers and clinicians, leading to great uncertainty and variability regarding the ideal treatment of these lesions. More recent literature2 recommends that Spitz tumors be viewed on a spectrum, with the common Spitz tumor on the benign end and its highly atypical counterpart, which cannot be distinguished from melanoma, on the other end of the spectrum.
They appear most commonly in the first and second decades of life, although new onset occurs in adulthood about 30% of the time.3 Both sexes are affected equally. The diagnosis is more common in fair-skinned and white people, although cases have been reported in the Hispanic population.4
Classic clinical presentation of a Spitz nevus is a fleshy, red-brown, erythematous or pigmented, hairless papule or nodule, ranging in size from 5 to 10 mm in diameter. Dermoscopy may aid in identifying pigment in an otherwise nonpigmented-appearing lesion. In children, these lesions most commonly occur on the face,5 although Spitz nevi have been seen on the arms and legs. These lesions appear suddenly and grow quickly over the course of several months to years, at which point they stabilize in size and appearance.
The differential diagnosis of Spitz nevus includes all pink, fleshy, or pigmented solitary lesions. Examples of these include intradermal nevus, molluscum contagiosum, juvenile xanthogranuloma, verruca vulgaris, amelanotic melanoma, dysplastic nevus, and pigmented basal cell carcinoma.
Biopsy technique is crucial to making the correct diagnosis. A small incisional shave or punch biopsy will not allow the pathologist to fully evaluate the architectural pattern for symmetry and circumscription of the lesion,6 possibly leading to a false and devastating diagnosis of malignancy. For this reason, conservative excisional biopsy is appropriate for lesions suspicious for Spitz nevus.
Biopsy samples should be examined by a dermatopathologist experienced with pigmented and Spitz nevi. The three most important histologic factors that may predict a poorer outcome are mitotic activity, mitoses near the base, and inflammation.2
There are no clear guidelines to direct the clinician in appropriate treatment of a Spitz nevus. Consideration must be given to the clinical scenario and histopathologic attributes of the lesion. Generally, Spitz nevi in the adult population are excised, whereas similar tumors in the pediatric population are usually managed nonsurgically with close observation,7 as several studies have found that younger age is more likely to be associated with benign Spitz nevus.8 Close communication between the clinician and dermatopathologist allows for collaborative discussion to determine the best treatment.
In our case, biopsy of the lesion on the young woman’s index finger revealed a Spitz nevus with unusual features. Risks and benefits of close observation versus surgical excision were discussed with the patient and her mother. They elected to see a plastic surgeon to undergo surgical excision, which was performed without any complication. In addition, the patient was instructed on the importance to return for annual skin examination.
Amelanotic melanoma (AMM) refers to a malignant melanoma tumor that lacks the presence of the characteristic melanin in classic melanomas. True amelanotic melanomas are rare9; more commonly, AMM refers to tumors that are mostly devoid of pigment, and close inspection reveals flecks of pigment at the periphery of the lesion. All forms of cutaneous melanoma, including the metastatic type, can have an amelanotic variant, although subungual and desmoplastic melanomas appear amelanotic at a significantly greater rate.10 AMM is the typical variant seen in albinism.3 AMM accounts for about 2% of all melanotic melanomas, affecting middle-aged women more commonly, with a 5:1 female:male ratio.11
Because of their relatively benign appearance, diagnosis of this melanoma is often delayed. For this reason, AMM is often referred to as the great masquerader.9 A history of a new pink growth or change in a pink, fleshy lesion should raise concern for malignancy, particularly in higher-risk patients, such as those with a personal or family history of melanotic melanoma and dysplastic nevi. Clinical presentation of AMM is a pink, erythematous, or flesh-colored macule, papule, patch, or plaque. The lesion may be smooth or scaly. Most AMMs will have flecks of pigment.
The differential diagnosis of AMM is vast. Mimickers include basal cell carcinoma, actinic keratosis, pyogenic granuloma, Spitz nevus, intradermal nevus, neurofibroma, molluscum contagiosum, eczema, psoriasis, and discoid lupus erythematosus.
Although dermoscopy is tremendously valuable in the evaluation of pigmented lesions, its use is limited in the evaluation of amelanotic melanomas. When using a dermoscope, care should be taken not to apply too much pressure to the lesion so as not to conceal the vascular pattern of the lesion. Pizzichetta and colleagues12 concluded that abnormal vascular patterns, such as milky-red dotted vessels, hairpin vessels, and linear irregular vessels were clues to the diagnosis of melanoma. Definitive diagnosis of AMM requires a skin biopsy for histopathologic evaluation. When AMM is suspected, excisional biopsy is the gold standard diagnostic test.13
Histopathologic examination of AMM reveals a host of changes including architectural disturbance and striking cytologic atypia. The majority of melanoma cells in AMM are of the epithelioid variety,14 presenting with abundant eosinophilic cytoplasm, prominent vesicular nuclei, and large nucleoli; others are of the spindle and desmoplastic morphology.
Despite the absence of clinically apparent pigmentation, AMM may reveal the presence of pigment on biopsy by use of special stains. The Fontana and the S-100 stain are helpful; however, electron microscopy is considered the most definitive method for diagnosis of AMM.15
The prognosis of AMM is the same as that of its pigmented counterpart in the same stage of growth. Morbidity and mortality depend on thickness and invasion of the tumor, as well as the patient’s age and sex.16 A higher mitotic index predicts a worse prognosis. Unfortunately, AMM is usually more advanced than pigmented melanotic melanoma at the time of diagnosis, likely due to the high rate of diagnostic confusion; therefore, prognosis is poorer.
The treatment of amelanotic tumors is the same as the treatment of pigmented melanotic melanoma. Wide local excision is the treatment of choice for AMM in situ. Depending on the stage of invasive AMM, treatment may involve wide local excision, lymph node dissection, radiation, immunotherapy, or other treatments.
In our case, the patient was referred to the local cancer center for treatment of his stage T1 AMM. He underwent wide local excision with negative margins. The patient was instructed regarding the need for monthly self-skin checks as well as clinical full skin examination every 3 months for the first years and then biannually thereafter.
Esther Stern, NP, is a family nurse practitioner at Advanced Dermatology & Skin Surgery, PC, in Lakewood, NJ
- Gelbard SN, Tripp JM, Marghoob AA, et al. Management of Spitz nevi: a survey of dermatologists in the United States. J Am Acad Dermatol. 2002;47(2):224-230.
- Luo S, Sepehr A, Tsao H. Spitz nevi and other Spitzoid lesions part I. Background and diagnoses. J Am Acad Dermatol. 2011;65(6):1073-1084.
- James WD, Berger TG, Elston DM. Andrews’ Diseases of the Skin: Clinical Dermatology. 11th ed. Philadelphia, PA: Saunders-Elsevier; 2011.
- Berlingeri-Ramos AC, Morales-Burgos A, Sánchez JL, Nogales EM. Spitz nevus in a Hispanic population: a clinicopathological study of 130 cases. Am J Dermatopathol. 2010;32(3):267-275.
- Paller AS, Mancini AJ. Hurwitz Clinical Pediatric Dermatology: A Textbook of Skin Disorders of Childhood and Adolescence. 4th ed. Philadelphia, PA; Elsevier Saunders; 2011.
- Ackerman AB. Spitz nevus. J Am Acad Dermatol. 1981;4(5):609-610.
- Luo S, Sepehr A, Tsao H. Spitz nevi and other Spitzoid lesions part II. Natural history and management. J Am Acad Dermatol. 2011;65(6):1087-1092.
- Vollmer RT. Patient age in Spitz nevus and malignant melanoma: implication of Bayes rule for differential diagnosis. Am J Clin Pathol. 2004;121(6):872-877.
- Koch SE, Lange JR. Amelanotic melanoma: the great masquerader. J Am Acad Dermatol. 2000;42(5):731-734.
- Baran R, Haneke E, Drapé JL, Zook EG. Tumours of the nail apparatus and adjacent tissues. In: Diseases of the Nails and Their Management. Baran R, Dawber RPR, de Berker DAR, Haneke E, Tosti A, eds. Oxford, United Kingdom; Blackwell Scientific; 1994.
- Conrad N, Jackson B, Goldberg L. Amelanotic lentigo maligna melanoma: a unique case presentation. Dermatol Surg. 1999;25(5):408-411.
- Pizzichetta MA, Talamini R, Stanganelli I, et al. Amelanotic/hypomelanotic melanoma: clinical and dermoscopic features. Br J Dermatol. 2004;150(6):1117-1124.
- Ming ME. The histopathologic misdiagnosis of melanoma: sources and consequences of “false positives” and “false negatives.” J Am Acad Dermatol. 2000;43(4):704-706.
- Cheung WL, Patel RR, Leonard A, et al. Amelanotic melanoma: a detailed morphologic analysis with clinicopathologic correlation of 75 cases. Cutan Pathol. 2012;39(1):33-39.
- Gibson LE, Goellner JR. Amelanotic melanoma: cases studied by Fontana stain, S-100 immunostain, and ultrastructural examination. Mayo Clin Proc. 1988;63(8):777-782.
- Schuchter L, Schultz DJ, Synnestvedt M, et al. A prognostic model for predicting 10-year survival in patients with primary melanoma. The Pigmented Lesion Group. Ann Intern Med. 1996;125(5):369-375.