Verruciform xanthoma overlying a long-standing inflammatory linear verrucous epidermal nevus

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Verruciform xanthoma (VX), an uncommon hyperplastic condition of the epithelium, usually presents as an asymptomatic solitary, sessile, or pedunculated lesion with a rough or pebbly surface, affecting age between 40 and 70 years.^[1] Local irritation or trauma initiates an inflammatory response, which leads to the formation of foam cells by the transformation of macrophages.^[1,2] VX is mainly seen in the oral mucosa; however, its presence overlying an inflammatory linear verrucous epidermal nevus (ILVEN) is rarely reported.^[2,3]

A 60-year-old female presented with a non-progressive, extremely itchy, verrucous plaque over the dorsum of her right hand extending to the forearm up to the elbow joint, and also over the right shin in a linear arrangement since her early childhood. For the past 1 year, verrucosity has increased in some areas of the plaque. There is no family history of similar complaints.

On examination, a well-defined, semi-adherent scaly plaque extending from the dorsum of the hand covering the wrist, extensor aspect of the forearm up to the right elbow joint with variable verrucosity [Figure 1a]. A similar, single, linear elevated distributed along the lines of Blaschko well-defined plaque with relatively less verrucosity was present over the anterior aspect of the right leg [Figure 1b]. No other systemic abnormality was found, including ophthalmic and neurological examination.

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Figure 1

(a): Linearly arranged, verrucous and scaly plaque extending from ring finger to extensor aspect of forearm of the right hand (yellow arrow); (b): Linearly arranged hyperpigmented, scaly and verrucous plaque over the right shin.

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On dermoscopy, showed white structureless areas, pigment globules, red dotted vessels in a patchy pattern, and yellow areas [Figure 2a].

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Figure 2

(a): Dermoscopy of the lesions shows white structureless areas (yellow arrow), pigment globules (black circle), dotted vessels in a patchy pattern (black arrow) and yellow areas (blue arrow) (Dermlite DL4 dermoscope, polarized microscopy, 10x); (b): Biopsy showed marked hyperkeratosis, parakeratosis, spongiosis, acanthosis. Upper dermis shows foamy histiocytes, occasional lymphocytes and neutrophils. Reticular dermis shows lympho-histiocytic perivascular infiltrate (H&E, 100x); (c): Foamy histiocytes (yellow circle), occasional lymphocytes and neutrophils along with acanthosis and spongiosis in the epidermis (H&E, 200x). H&E: Hematoxylin and eosin.

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A 4 mm biopsy was performed from the verrucous part of the plaque over the dorsum of the right hand [Figure 1a] revealed marked hyperkeratosis, papillomatosis, parakeratosis, spongiosis, and acanthosis along with neutrophilic collection in the stratum corneum. Papillary dermis showed foamy histiocytes, occasional lymphocytes, and neutrophils. Reticular dermis showed lymphohistiocytic perivascular infiltrate [Figure 2b and c]. There were no limb defects or bony abnormalities on clinical and radiological examination.

Based on the clinical, dermoscopic, and histopathological correlation, the diagnosis of “VX overlying ILVEN” was made. The patient was advised to apply clobetasol propionate 0.05% with salicylic acid 6% ointment once daily, along with tablet levocetirizine 10 mg at night and moisturizer for 6 weeks, and she was informed about the benign nature of this disease. At follow-up, she had good improvement in itching, scaling, and thickness of the plaque.

Shafer gave the initial description of this condition 1971. This rare transformation occurs in about 0.025–0.05% of cases. From a clinical standpoint, oral VX is similar to cutaneous or extraoral/extragenital VX. Extraoral nevi, lymphedema, congenital hemidysplasia with ichthyosiform erythroderma, and limb abnormalities syndrome are commonly linked to extraoral lesions.^[1,4] Anogenital mucosa and the scrotum are typically involved in extraoral cases. Rarely, extraoral extragenital cases are reported in the literature.^[1,2,5]

Dermoscopic features include white structureless areas, pigment globules, dotted vessels in a patchy pattern, and yellow areas, which have been mentioned in a case report by Swathi et al.^[4] which corresponds to our case.

Both the pathophysiology and etiology are still unknown. The presence of foam cells in the papillary dermis between the epithelial rete ridges is the hallmark of diagnosis.^[1] These foam cells can be stained with cluster of differentiation 68 (CD68), indicating that they are descended from monocytes or macrophages. However, as of yet, no evidence of a cancerous possibility has been documented.^[5] Surgical excision, ablative CO₂ laser, cryotherapy, and dermabrasion are some treatment modalities apart from topical corticosteroids or retinoids.^[6] To the best of our knowledge, few cases were reported about VX overlying ILVEN. This case increases the awareness among dermatologists about this rare benign transformation.