AUTHORS:
Alexander K. C. Leung, MD
Clinical Professor of Pediatrics, University of Calgary; Pediatric Consultant, Alberta Children’s Hospital, Calgary, Alberta, Canada

Benjamin Barankin, MD
Dermatologist, Medical Director and Founder, Toronto Dermatology Centre, Toronto, Ontario, Canada

Kin Fon Leong, MD
Pediatric Dermatologist, Pediatric Institute, Kuala Lumpur General Hospital, Kuala Lumpur, Malaysia

CITATION:
Leung AKC, Barankin B, Leong KF. An atlas of nail disorders, part 2. Consultant. 2019;59(12):36-360, 364.

EDITOR’S NOTE: This article is part 2 of a 15-part series of Photo Essays describing and differentiating conditions affecting the nails. Parts 3 through 15 will be published in upcoming issues of Consultant. To access previously published articles in the series, visit the Consultant archive at www.Consultant360.com and click the “Journals” tab.

Median Nail Dystrophy

Median nail dystrophy—also known as dystrophia unguium mediana canaliformis, nevus striatus unguis, or median canaliform dystrophy of Heller—is characterized by a midline or paramedian split, or ridge and canal formation in the nail plate of one or more nails, beginning at or distal to the proximal nail fold (Figure).^1-3 Median nail dystrophy is uncommon; the exact incidence is not known. There is no sex predilection. The mean age of occurrence is 25.7 years.¹

The exact etiology is not known, and most cases of median nail dystrophy are idiopathic.^2-4 Presumably, the condition results from a temporary defect in the nail matrix that interferes with nail formation.^1,5 Median nail dystrophy may result from dyskeratinization, focal infection, cryotherapy, or repeated self-inflicted trauma to the nail or nail bed in the form of pushing down the proximal nail fold and cuticle (eg, habitual picking).^1,6-8 The condition may also result from subungual tumors (eg, glomus tumor, myxoid cyst, papilloma), systemic isotretinoin therapy, systemic alitretinoin therapy, or systemic ritonavir therapy.^4,6,9-12 Familial occurrences have rarely been reported.³

Histologically, parakeratosis and accumulation of melanin can be seen within and between the keratinocytes in the nail bed.¹ The absence of adhesions between keratinocytes within the nail matrix with dyskeratosis may be responsible for the formation of longitudinal groove and splitting of the nail plate.¹

Clinically, median nail dystrophy presents as a single midline or paramedian split, or ridge and canal formation in the nail plate of one or more nails, beginning at or distal to the proximal nail fold.³ Multiple parallel transverse cracks or fissures that extend laterally and obliquely from the central canal or split toward the nail edge are often observed, giving rise to the characteristic appearance of an inverted fir tree or Christmas tree.^6,9,13 The condition is usually symmetric and most often affects the thumbnails, although other fingernails or toenails may be involved.¹ Rarely, the condition may involve both thumbnails and great toenails simultaneously.^5,6,12,13 Thickening of the proximal nail fold, enlargement of the lunula, and redness of the lunula may occur.^1,3 The condition is usually asymptomatic.

The diagnosis is mainly clinical, and no laboratory test is necessary for diagnosis. The main differential diagnosis is habit tic deformity.¹

Median nail dystrophy tends to resolve spontaneously over a period of months to years.^2,5,8 However, the condition can be recurrent.^1,8

Median nail dystrophy is considered a benign condition. As such, no treatment is necessary. The underlying cause, if identified, should be removed if possible. If treatment is desired for cosmesis, one may consider the use of topical calcineurin inhibitors (ie, tacrolimus and pimecrolimus), although publications related to successful treatment options are greatly lacking.^2,5 Other treatment modalities include a potent topical corticosteroid, intralesional corticosteroid, topical tazarotene, topical psoralen plus UV-A, and 1064-nm quasi long-pulsed Nd:YAG laser.¹⁴ In general, treatment is often prolonged and unsatisfactory.⁶ 

REFERENCES:

1. Kota R, Pilani A, Nair PS. Median nail dystrophy involving the thumb nail. Indian J Dermatol. 2016;61(1):120.
2. Madke B, Gadkari R, Nayak C. Median canaliform nail dystrophy of Heller. Indian Dermatol Online J. 2012;3(3):224-225.
3. Sweeney SA, Cohen PR, Schulze KE, Nelson BR. Familial median canaliform nail dystrophy. Cutis. 2005;75(3):161-165.
4. Dharmagunawardena B, Charles-Holmes R. Median canaliform dystrophy following isotretinoin therapy. Br J Dermatol. 1997;137(4):658-659.
5. Hoy NY, Leung AKC, Metelitsa AI, Adams S. New concepts in median nail dystrophy, onychomycosis, and hand, foot, and mouth disease nail pathology. ISRN Dermatol. 2012;2012:680163. doi:10.5402/2012/680163.
6. Pathania V. Median canaliform dystrophy of Heller occurring on thumb and great toe nails. Med J Armed Forces India. 2016;72(2):178-179.
7. Perrin AJ, Lam JM. Habit-tic deformity. CMAJ. 2014;186(5):371.
8. Winther AH, Bygum A. Can median nail dystrophy be an adverse effect of alitretinoin treatment? Acta Derm Venereol. 2014;94(6):719-720.
9. Alli N, Dogan S. Short-term isotretinoin-induced elkonyxis and median nail dystrophy. Cutan Ocul Toxicol. 2016;35(1):85-86.
10. Avhad G, Ghuge P. Median canaliform dystrophy of Heller. Indian Pediatr. 2013;50(11):1073.
11. Borges-Costa J, Sacramento Marques M. Median nail dystrophy associated with ritonavir. Int J Dermatol. 2013;52(12):1581-1582.
12. Damevska K, Duma S, Pollozhani N. Median canaliform dystrophy of Heller after cryotherapy. Pediatr Dermatol. 2017;34(6):726-727.
13. Latham L, Langley R. Can you identify this condition? Median canaliform nail dystrophy. Can Fam Physician. 2013;59(5):511, 513.
14. Choi J-Y, Seo H-M, Kim W-S. Median canaliform nail dystrophy treated with a 1064-nm quasi-long pulsed Nd:YAG laser. J Cosmet Laser Ther. 2017;19(4):225-226.

NEXT: Habit Tic Deformity

Habit Tic Deformity

Habit tic deformity of the nail, also known as onychotillomania, is a nail deformity characterized by central linear depression of the nail plate, often accompanied by multiple transverse ridging/depressions fairly evenly spaced along the nail plate, both of which run from the nail fold to the distal edge of the nail.^1,2 The transverse ridging/depressions resembles a washboard (Figure 1).

Figure 1.

The depth of the central depression depends on the intensity and duration of the inflicted trauma to the proximal nail fold (Figures 1 and 2). The condition is usually symmetric, and involvement of both thumbnails is classical.^2,3 Rarely, toenails can also be affected.³

Figure 2.

Although habit tic deformity of the digit has been reported in children, the condition is more common in individuals from the second to fourth decades of life.^3,4 Thickening of the proximal nail fold, enlargement of the lunula, and redness of the lunula are characteristic.⁵ The cuticle is often detached and damaged. With progression of the disease, the cuticles may eventually disappear.^3,6

Habit tic deformity is caused by habitual external trauma to the nail matrix, such as manipulating the proximal nail fold or periungual area, usually with the tip of an adjacent finger (usually the index finger) or contralateral thumbnail.^2,7 At times, habitual picking of the proximal nail fold may result from an obsessive-compulsive behavior.^3,8 Rarely, the condition can be secondary to guitar playing.⁹

The nails seen in habit tic deformity lack the characteristic longitudinal splitting and inverted fir tree or Christmas tree pattern of oblique ridges running outward and proximally seen in median nail dystrophy.^1,3 The spontaneous resolution once self-manipulation has ceased further differentiates habit tic deformity from median nail dystrophy. Occasionally, habit tic deformity and median nail dystrophy may coexist.¹⁰ Some authors believe that the two conditions are part of a spectrum of the same disorder.⁵

For treatment, further trauma to the nail such as nail picking should be discontinued. Physical barrier to prevent nail picking such as application of bandage, tape, or instant glue (cyanoacrylate adhesive) to the nail folds may be useful.^2,3 For those cases that result from obsessive-compulsive behavior, the use of selective serotonin-reuptake inhibitors may be considered.^2,3,6 The nail usually returns to normal several months after cessation of nail fold picking, as the new nail would not be affected.¹¹ Relapses are common.¹²

REFERENCES:

1. Latham L, Langley R. Can you identify this condition? Median canaliform nail dystrophy. Can Fam Physician. 2013;59(5):511, 513.
2. Perrin AJ, Lam JM. Habit-tic deformity. CMAJ. 2014;186(5):371.
3. Singal A. Habit tic deformity of bilateral thumb and toenails in a young boy: an unusual occurrence. Skin Appendage Disord. 2017;3(4):186-187.
4. El-Heis S, Abadie A. Habit tic nail deformity—a rare presentation in an 8 year old boy. Dermatol Online J. 20165;22(11). pii: 13030/qt16j6x5n3.
5. Mooney E, Mahar P, Howard A. Median canaliform and habit-tic deformity of the nail: is there an association with macrolunulae? Australas J Dermatol. 2016;57(4):319-320.
6. Vittorio CC, Phillips KA. Treatment of habit-tic deformity with fluoxetine. Arch Dermatol. 1997;133(10):1203-1034.
7. Kota R, Pilani A, Nair PS. Median nail dystrophy involving the thumb nail. Indian J Dermatol. 2016;61(1):120.
8. Sonthalia S, Sharma P, Kapoor J, Singh P. Habit tic deformity: need for a comprehensive approach. Skin Appendage Disord. 2019;5(2):117-118.
9. Wu JJ. Habit tic deformity secondary to guitar playing. Dermatol Online J. 2009;15(3):16.
10. Wang C, Lee S, Howard A, Foley P. Coexisting median canaliform nail dystrophy and habit-tic deformity in a patient with atopic dermatitis [published online June 3, 2019]. Australas J Dermatol. doi:10.1111/ajd.13084.
11. Lipner SR. Habit tic nail deformity. J Cutan Med Surg. 2018;22(2):222.
12. Griego RD, Orengo IF, Scher RK. Median nail dystrophy and habit tic deformity: are they different forms of the same disorder? Int J Dermatol. 1995;34(11):799-800.