Cryotherapy as a treatment modality for Bowen’s disease: A case report

INTRODUCTION

Bowen’s disease (BD) is a non-invasive intraepidermal squamous cell carcinoma that typically presents as a slowly enlarging, erythematous, scaly plaque, clinically asymptomatic or mildly symptomatic, having a chronic course and usually misdiagnosed as eczema. It is considered a squamous cell carcinoma in situ, with the potential for progression to invasive disease if left untreated. Several risk factors have been implicated in its pathogenesis, including chronic sun exposure, arsenic exposure, immunosuppression, and infection with human papillomavirus (HPV).^[1]

Although BD most commonly arises on sun-exposed areas of the skin in elderly individuals, it can occasionally present on non-sun-exposed sites. Histopathological examination remains the gold standard for diagnosis.^[2]

In this case report, we describe a case of BD over a non-sun-exposed area. The patient had no history of immunosuppressant use or prior HPV infection, highlighting an atypical presentation of the disease.

CASE REPORT

A 71-year-old female with controlled hypertension, type 2 diabetes mellitus, and no prior history of immunosuppressant therapy presented with a gradually enlarging erythematous lesion over her left thigh, first noted 1 year prior with mild pruritus. The lesion began as a small plaque and progressively increased in size. She consulted a physician for the lesion and was given topical medication (details not furnished), but found no relief.

Clinical examination

A single, well-demarcated, 5 × 3 cm erythematous scaly indurated plaque with crusting was noted on the left thigh [Figure 1]. Inguinal lymph nodes were not enlarged.

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Figure 1: Scaly plaque with crusting.

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Clinical differential diagnosis considered for this case includes psoriasis, nummular eczema, and seborrheic keratosis.

Histopathology

Skin biopsy (5 mm punch biopsy from the lateral aspect of the left thigh) revealed an epidermal proliferation comprising thickening and irregular elongation of rete ridges, some of which were confluent. Keratinocytes displayed moderate nuclear pleomorphism, loss of polarity, crowding, and atypia throughout the epidermis. Scattered pyknotic and dyskeratotic cells were present. The dermis exhibited a lichenoid inflammatory infiltrate comprising lymphocytes and plasma cells [Figures 2 and 3].

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Figure 2: Histopathology of Bowen’s disease. Nuclear atypia (orange arrow) and dyskeratotic cells (blue arrow). (Hematoxylin and eosin stain, 10x).

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Figure 3: Histopathology of Bowen’s disease. Keratinocytes with nuclear polymorphism and crowding (green arrow). (Hematoxylin and eosin stain, 10x).

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Follow-Up

Two-month post-treatment, the lesion demonstrated a tendency toward spontaneous regression, presenting as post-inflammatory hypopigmentation and hyper-pigmentation^[5] [Figure 4].

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Figure 4: Treatment and follow-up. (a): After 1^st sitting of cryotherapy (blister formation); (b): After 2^nd sitting of cryotherapy (scaling and crusts); (c): Resolution (post-inflammatory hypo- and hyperpigmentation).

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DISCUSSION

BD is an early form of cutaneous squamous cell carcinoma in situ with no lymphatic involvement unless progression to invasive squamous cell carcinoma occurs. Typically affects individuals over 60 years of age.^[2,3] This case illustrates the classic presentation and evolution of BD.

Dermoscopy was not done in our case; however, it facilitates early detection of squamous cell carcinoma. Usual dermoscopic finding includes brown keratotic structureless area with clustered brown to blue-gray dots and globules and clustered glomerular vessels.^[6]

Cryotherapy, a destructive treatment, induces necrosis through intracellular ice formation and vascular stasis.^[3,4]It is effective, especially in patients where surgical excision may be contraindicated.^[5] The patient experienced clinical improvement in regression of lesion over a period of one month. Wound healing was faster with cryotherapy compared to radiotherapy, but slower than the curettage and cautery regimen.^[7]

Alternative treatment options include topical 5% imiquimod cream, surgical excision, and photodynamic therapy, which have shown variable efficacy and recurrence rates. Guidelines recommend careful selection of therapy based on lesion size, site, patient comorbidities, and preferences.^[8]

According to the study by Sirka et al.^[9], three cases of BD involving non-sun-exposed sites were reported with lesions located on the lower back, glans penis, and right thigh. Similarly, Nagakeerthana et al.^[10] documented two cases with lesions over the buttocks and left submammary region.

We are reporting this case because:- 1)Lesions occurred over a non-sun-exposed site (thigh),which is an uncommon location and posed a diagnostic challenge; 2) No evidence of immunocompromised state or HPV infection and 3) Lesions responded well to cryotherapy using liquid nitrogen, demonstrating it as an effective, non-invasive treatment modality in cases reluctant to undergo surgery.

LIMITATION

In this case of BD, dermoscopy and immunohistochemistry were not performed.

CONCLUSION

The asymptomatic course, subtle and non-specific early features, and diverse clinical presentations of BD make its diagnosis challenging. Given the potential for transformation into invasive cancer, prompt recognition and early intervention are crucial.

Histopathology is essential for the diagnosis of BD. Individualized treatment and follow-up strategies are vital to ensure optimal clinical outcomes. This case demonstrates the effectiveness of cryotherapy in managing BD, especially for small lesions located in well healing site. Its low cost and non-invasive nature further support its role as a favorable therapeutic alternative.