Acral reed nevus with parallel ridge pattern: an exception to the rule of malignancy^☆

Dear Editor,

Reed nevi (RNs) are almost exclusively junctional neoplasms distinguished as a variant of Spitz nevus (SN) by their significant melanogenesis and growth pattern. Acral presentation of SN is rare and has specific clinical and histopathological features.¹ Nonetheless, dermoscopic findings of SN and its variants on the acral skin are poorly documented.² Herein we describe a case of RN on the volar skin of a finger in which parallel ridge pattern was observed by dermoscopic examination.

A 9-year-old boy presented with an asymptomatic pigmented lesion on his right hand. He had detected the lesion 8 months previously and had enlarged gradually. He had no personal or family history of malignant tumors. Physical examination revealed an asymmetrical dark brown macule, 13×3mm in size, located on the volar region of the second right finger. The lesion exhibited an atypical linear morphology similar to a crescent moon (Fig. 1A). Dermoscopic findings showed a brownish parallel ridge pattern with some streaks at the periphery (Fig. 1B). A complete surgical excision was done to rule out malignancy. Histological examination revealed several small nests, vertically oriented, composed of heavily pigmented spindled melanocytes along the dermo-epidermal junction (Fig. 1CD). No melanocytes were seen in the dermis. A diagnosis by an RN was done.

Figure 1
Reed nevus on the finger (A) Clinical features of the lesion. (B) Dermoscopic findings show a parallel ridge pattern with some peripheral streaks. (C) Histopathological findings were tumor cell nests scattered within the epidermis (Hematoxylin & eosin, ×100). (D) Junctional nests were composed of heavily pigmented spindle-shaped melanocytes, vertically oriented (Hematoxylin & eosin, ×200).

Acral SNs understood by those located on soles, palms and fingers are infrequent, being reported to comprise less than 2% of all SNs.¹ They are more common in young female adults, more frequently located on the feet, and larger than acral melanocytic nevi.¹ Acral RN or “pigmented spindlecell nevus” is the most common variant of SN that typically presents as a heavily pigmented lesion.¹ Given the overlapping clinicopathologic features with malignancy, their clinical diagnosis is often of an atypical nevus or a malignant melanoma.¹, ² Dermoscopic examination is useful in differentiating RN and acral lentiginous malignant melanoma.² Dermoscopic patterns most commonly associated with SN are starburst and globular patterns.² However, a characteristic pattern upon dermoscopic examination of SN localized on the glabrous skin has not been described.², ³ A review of the literature revealed only nine cases of acral SN and its variants with the dermoscopic examination.⁴ A parallel furrow pattern with peripheral dots, streaks, and projections and a starburst pattern has been reported in four and three cases, respectively.⁴ A crista-dotted pattern was described in one case of SN on the palm.³ Only Jurakić et al. in 2018 reported a young female with a rapidly growing plantar pigmented SN that had a dermoscopic parallel ridge pattern with few peripheral globules, similar to our case.⁵

In conclusion, we report a case of an acral RN showing a parallel ridge pattern on dermoscopy, an exception to the rule of malignancy. The present report aims to highlight that, although such a pattern is highly suggestive of melanoma, it can also be seen in a proportion of acral SNs localized on the glabrous skin. However, an SN with asymmetry and/or atypical dermoscopic pattern is impossible to differentiate from melanoma and, thereby, must be excised irrespective of age or clinical morphology.

• Financial support
  None declared.
• ☆
  Study conducted at the Department of Dermatology, Arnau de Vilanova University Hospital, Lleida, Spain.

References

• ¹
  Requena C, Requena L, Kutzner H, Yus ES. Spitz nevus: a clinicopathological study of 349 cases. Am J Dermatopathol. 2009;31:107–16.
• ²
  Lallas A, Apalla Z, loannides D, Lazaridou E, Kyrgidis A, Broganelli P, et al. Update on dermoscopy of Spitz/Reed naevi and management guidelines by the International Dermoscopy Society. Br J Dermatol. 2017;177:645–55.
• ³
  Nakagawa K, Kishida M, Okabayashi A, Shimizu N, Taguchi M, Kinoshita R, et al. Spitz nevus on the palm with crista tranverse dots/dotted lines revealed by dermoscopic examination. J Dermatol. 2015;42:649–50.
• ⁴
  Montenegro Jaramillo SE, Jo G, Darmawan CC, Lee C, Mun J-H. Dermoscopic findings of Spitz nevus on acral volar skin. Indian J Dermatol Venereol Leprol. 2019;85:629–32.
• ⁵
  Jurakić Tončić R, Bradamante M, Ferrara G, Štulhofer-Buzina D, Petković M, Argenziano G. Parallel ridge dermoscopic pattern in plantar atypical Spitz nevus. J Eur Acad Dermatol Venereol. 2018;32:e86–121.

Publication Dates

• Publication in this collection
  07 Apr 2023
• Date of issue
  Mar-Apr 2023

History

• Received
  05 Feb 2021
• Accepted
  01 May 2021
• Published
  03 Jan 2023