Multicentric squamous cell carcinoma arising on psoriatic plaque.

Sir,

Psoriasis is a chronic skin condition characterized by epidermal hyperproliferation and altered expression of about 1,300 genes.[1] It is consistently associated with many cutaneous and systemic diseases. Patients with psoriasis are at an increased risk of developing cutaneous malignancy, especially non-melanoma skin cancers and lymphoproliferative disorders. The risk is highest for those with severe psoriasis and also for patients treated with PUVA, methotrexate, topical tar, and biologicals. A 62-year-old farmer presented in our OPD with 10 years’ history of psoriasis over knees and elbows. For the last 2 years, he developed a cauliflower-like growth on each elbow over the pre-existing lesion of psoriasis. Before coming to us, he had received only homeopathic treatment without any relief. He did not have any physical signs of arsenicosis, and there was no history of arsenicosis in his locality. There was no family history of psoriasis or of malignancy. Physical examination revealed dirty white verrucous growths over both the psoriatic plaques, measuring around 10 cm by 6 cm on right elbow and around 7 cm by 5 cm on left elbow. The lesions were firm to hard in consistency, not fixed to underlying fascia, muscle, or bone, and there was sero-sanguineous oozing on the right side [Figure 1]. The skin surrounding the growths showed well-defined erythematous plaques with silvery scales. Systemic examination revealed nothing relevant, except multiple firm discrete mobile lymph nodes over both axillae.

Figure 1

Verrucous growths on both the elbows overlying psoriasis plaques

Routine hematological and biochemical investigations were within normal limits. Histopathology of a biopsy from both the growths revealed features suggestive of well-differentiated squamous cell carcinoma (SCC) [Figures 2 and 3]. Histopathology of a biopsy from clinically psoriasis-like lesions outside the margins of the growth on left elbow revealed typical features of psoriasis [Figure 4]. Fine needle aspiration cytology from an enlarged axillary lymph node revealed reactive follicular hyperplasia and no malignant cells. We referred the case to surgical department for further management.

Figure 2

Histopathology of the growth on right elbow

Figure 3

Histopathology of the growth on left elbow

Figure 4

Histopathology of the psoriasis lesion at the periphery of the growth on left elbow

The exact incidence of SCC in patients with psoriasis is not known. Olsen et al. in their hospital-based study found SCC in 1% of their patients.[2] Recent studies have shown increased expression of proliferation regulators like Keratin 16, WNT 5A, defensin B4, SERPIN B3, STAT-1 in both psoriasis and SCC.[3] It has also been shown that epidermal proteins like serpin, a squamous cell carcinoma antigen, bind IgG from psoriatic serum.[4] In biopsy specimens of psoriasis and cutaneous neoplasia, persistent activation of Src-family tyrosine kinases (SFKs), known regulators of keratinocyte growth and differentiation, has been shown in another study.[5] Thus, study of literature provides evidence of the presence of various factors conducive for the development of SCC of the skin in patients suffering from psoriasis.

We report the present case considering the rarity of reports describing multiple SCC in a patient of psoriasis not treated with therapeutic modalities that predispose to SCC, and emphasize the necessity of histopathological study of longstanding psoriatic plaques.