Case presentation
In this case we report a 45‑year‑old patient with untreated psoriasis who referred to dermatology inpatient department due to erythrodermic psoriasis, through further evaluation several biopsy specimens were taken from patient and the result of scalp biopsy was reported to be SCC. Although this type of NMSC is prevalent among under treatment psoriatic patients, our case had not received any systemic therapy or phototherapy. The patient was a 45‑year‑old, mental retard male, referred to the dermatology inpatient department due to erythrodermic psoriasis. He was a smoker, unemployed and poor hygiene person who did not follow up his medical condition over the years. Through his admission, complete history was taken and it revealed that he was suffering from localized plaque-type psoriasis for 10 years and was only under treatment of topical corticosteroids including triamcinolone or clobetasol two or three times per day as well as topical calcitriol and emollients. The patient had no history of phototherapy or any oral antipsoriatic agents. Family history of psoriasis, skin cancers and other related disorders was also negative. Through admission the patient had low grade fever and malaise. On dermatological examination we found diffuse erythematous scaly eruptions over his scalp, trunk and bilateral extremities, involving 90% of the body surface area [Figure 1, 2]. They were associated with moderate to severe pruritus. A 6 x 5 cm erythematous, firm, proliferative growth, adherent to the underlying structures was present over the frontal part of his scalp for 2 years. Furthermore multiple crusted tumoral lesions were existent diffusely on the scalp [Figure 3]. These lesions were not related to previous psoriatic plaques. No lymphadenopathy or mucosal involvement were detected. Nails pitting and onycholysis were seen in hand and toe nails. Other evaluations including complete blood cell count, electrocardiogram and brain CT scan were normal. Multiple skin biopsies were taken from his scalp and trunk, histopathological investigation of scalp specimen revealed neoplastic proliferation of epithelial cells with pushing border and surface ulceration in focal area and clear cell changes in some area. Neoplastic pleomorphism cells had vesiculated nuclei and marked mitotic figure was also seen. In another pieces tumoral bulk did not have attachment to epidermis [Figure 4]. IHC staining showed strongly positive P63, positive EMA and CK and negative Ber-EP4. These findings were more favor for squamous cell carcinoma with sebaceous differentiation. Trunk skin lesion biopsy findings were also consistent with psoriasis [Figure 5]. Eventually the largest tumoral lesion was removed through Mohs surgery. Other lesions treated with intralesional injection of interferon alfa-2a 1.5 million units twice a week.