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Sparking the interest in Spark nevus

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By Jason B. Lee, MD, FAAD
Dec. 13, 2023
Vol. 5, No. 49

Dr. Jason Lee - DermWorld Insights and Inquiries
The late A. Bernard Ackerman has described and named a variety of dermatologic entities, expanding the lexicon of dermatology over his career. He has been known to come up with catchy and playful names for dermatologic entities such as jentigo and compendigo, a melanocytic nevus that has combined histopathologic features of simple lentigo and junctional or compound melanocytic nevus. (1) He has been credited also for introducing the term Spark nevus for a melanocytic nevus with combined histopathologic features of Spitz nevus and Clark/dysplastic nevus. In 2009, the term was formally introduced in the literature by Ko and colleagues in a case series of 27 examples of the nevi. (2) Rare case reports and case series have been published subsequently. (3-7) In 2021, a case series of 12 lesions was published and, more recently in 2023, Massone and coworkers published a series of 20 cases with an emphasis on the dermatoscopic findings. (6,7)

Spark nevus usually occurs in adults in their 30s on the trunk and lower extremities. The nevus is small, ranging from 3 to 10 mm with a reported mean size less than 6 mm. Clinically, the nevus is usually unevenly pigmented, having areas of dark and light color. Atypical nevus is the usual clinical diagnosis and the reason for its biopsy. Histopathologically, there is a well-circumscribed junctional melanocytic proliferation of spindled and epithelioid spitzoid melanocytes with a regularly nested pattern. Horizontal orientation with a striking flat base of the junctional component is emphasized. (2)

Image of Spark nevus for DWII
Image of histopathology for Spark nevus in DWII

In the most recent case series, Masson and colleagues reported a frequent history of sunburn and high nevus count in their patients as well as BRAF mutation in 7 out of the 10 cases that were tested. (7) They observed both typical and atypical dermatoscopic structures. The atypical dermatoscopic structures included atypical pigment network, irregular globules, dots and blotches, blue-whitish veil, irregular hyperpigmented areas, and regression. The authors assert that the clinically uneven pigmentation and the atypical dermatoscopic structures are responsible for their biopsy. Histopathologically, the nevi were small, symmetric, and sharply circumscribed with uniform cytology, all indicative of a benign melanocytic process. They also reported good clinical outcome with no evidence of recurrence, similar to the previous two case series, confirming the benign nature.

Though Spark nevus is reported to be rare, the nevus may not be so rare. The authors of all three case series acknowledge that the Spark nevus is underdiagnosed by dermatopathologists and that the histopathologic pattern is routinely encountered in the daily dermatopathology practice. (2,6,7) The nevus may have been reported under other synonyms or categories of melanocytic neoplasms that include Clark/dysplastic nevus, spitzoid Clark nevus, Spitz nevus, early Reed nevus, atypical Spitz nevus, and even melanoma, particularly for those cases with some pagetoid spread depending on the criteria applied and threshold of the dermatopathologist. This is not unexpected since pathologic diagnosis of melanocytic neoplasms is a highly subjective discipline and agreement among pathologists in the diagnosis of flat small melanocytic neoplasms is poor. In the largest concordance study of melanocytic neoplasms among pathologists, Elmore and colleagues reported a poor concordance rate for dysplastic nevus or atypical nevus of any grade, Spitz nevus, and melanoma in-situ, questioning the validity of the very gold-standard in diagnosing melanocytic lesions. (8) For all the Spark nevi included in the three cases series, they all may not be classified as the same nevus by other dermatopathologists. While in the initial case series by Ko and colleagues reported some degree of scatter or pagetoid spread in all their lesions, the subsequent series only described a well-nested pattern and appears to have excluded lesions with pagetoid spread. As any degree of pagetoid spread is usually interpreted as an atypical histopathologic finding that results in excision recommendation, those lesions with pagetoid spread may have been classified under different designations.

The principal aim of the first case series by Ko and colleagues was to increase the awareness of a melanocytic nevus that has a combined histopathologic pattern and to minimize its overdiagnosis and overtreatment. In their words, “Classification is inherently arbitrary. We take no issue with classification of these lesions as Spitz nevi with a particular (flat/horizontal) architectural pattern. We do argue against diagnosing these lesions as an aggressively behaving melanocytic process such as melanoma as our experience suggests that these lesions exhibit no aggressive behavior.” Clinicians can decrease the odds of overdiagnosis by making sure that the biopsy specimen has some normal skin around the pigment. This will ensure histopathologic assessment of the fundamental benign features of this nevus — small size, symmetry, and sharp circumscription.

Point to Remember: For the clinician, a Spark nevus may have been encountered under different designations such as Clark/dysplastic nevus and Spitz nevus assigned with varying degree of atypia. The designation Spark nevus accounts for a combination of histopathologic findings present in Spitz and Clark nevus long observed by pathologists. Though the nevus may harbor atypical dermatoscopic features, a Spark nevus is fundamentally benign both clinically and histopathologically.

Our experts’ viewpoint

Christine Ko, MD, FAAD
Professor of Dermatology and Pathology
Yale School of Medicine

Jennifer McNiff, MD
Professor of Dermatology and Pathology; Director, Yale Dermatopathology Laboratory; Section Chief, Dermatopathology
Yale School of Medicine

“Spark” nevus is a catchy name that many dermatopathologists recognize as a descriptive diagnosis for a melanocytic lesion that has Clark/dysplastic architectural features (fusion of nests at the bases of elongated rete, creating a flat base to the junctional component) and Spitzoid (epithelioid to spindled) cytology. As Dr. Lee comments, the term “Spark” nevus is not necessarily a widely adopted term in use in general practice, as depending on training and variable emphasis on architecture vs. cytology, lesions that can be categorized as a “Spark” nevus may be instead reported as a benign or malignant lesion in the category of Clark/dysplastic nevus, Spitz nevus, another type of Spitzoid lesion (e.g. atypical Spitz tumor), melanocytoma, or even malignant melanoma. Increasing use of molecular testing may aid in more uniform categorization of this type of melanocytic nevus; MAP2K1 mutations have been described in one series, (9) and the presence of BRAFV600E mutations in 7/10 lesions suggests that “Spark” nevus should be categorized with dysplastic nevus rather than true Spitz nevi. (7) Ultimately, recognition of “Spark” nevus by dermatologists, via the clinical and dermoscopic features described here in combination with buzzwords in the histopathology report like Clark/dysplastic and Spitz/Spitzoid, may help prevent overdiagnosis of truly benign lesions.

  1. Maize JC, Ackerman AB. Chap 4: Benign proliferation of melanocytes. In: Pigmented lesions of the skin. Lea & Febiger; 1987: p.82.

  2. Ko CJ, McNiff JM, Glusac EJ. Melanocytic nevi with features of Spitz nevi and Clark's/dysplastic nevi ("Spark's" nevi). J Cutan Pathol. 2009;36(10):1063-1068. doi:10.1111/j.1600-0560.2008.01221.x.

  3. Biondo G, Gnone M, Sola S, Pastorino C, Massone C. Dermoscopy of a Spark's nevus. Dermatol Pract Concept. 2018;8(2):126-128. Published 2018 Apr 30. doi:10.5826/dpc.0802a11.

  4. Park JB, Seong SH, Jang JY, Yang MH, Suh KS, Jang MS. A Case Report on the Dermoscopic Features of Spark's Nevus. Ann Dermatol. 2020;32(3):233-236. doi:10.5021/ad.2020.32.3.233.

  5. Blum A, Viehmann M, Paredes BE. Vom Hund über die Dermatoskopie zum Spark-Nävus [From dog sniffing via dermoscopy to dysplastic nevus]. Hautarzt. 2022;73(1):88-92. doi:10.1007/s00105-021-04865-7.

  6. Cimmino A, Cazzato G, Colagrande A, et al. Spitz Nevus with Features of Clark Nevus, So-Called SPARK Nevus: Case Series Presentation with Emphasis on Cytological and Histological Features. Dermatopathology (Basel). 2021;8(4):525-530. Published 2021 Dec 1. doi:10.3390/dermatopathology8040055.

  7. Massone C, Stanganelli I, Ingordo V, et al. Clinicopathologic and Dermoscopic Features of 20 Cases of Spark's Nevus, a Dermoscopic Simulator of Melanoma. Am J Dermatopathol. 2023;45(3):153-162. doi:10.1097/DAD.0000000000002323.

  8. Elmore JG, Barnhill RL, Elder DE, et al. Pathologists' diagnosis of invasive melanoma and melanocytic proliferations: observer accuracy and reproducibility study. BMJ. 2017;357:j2813.

  9. Donati M, Nosek D, Waldenbäck P, Martinek P, Jonsson BA, Galgonkova P, Hawawrehova M, Berouskova P, Kastnerova L, Persichetti P, Crescenzi A, Michal M, Kazakov DV. MAP2K1-Mutated Melanocytic Neoplasms With a SPARK-Like Morphology. Am J Dermatopathol. 2021 Jun 1;43(6):412-417. doi: 10.1097/DAD.0000000000001840. PMID: 33264134.

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