Coexistence of psoriasis and primary high-grade subcutaneous leiomyosarcoma.

Sir,

Psoriasis is a chronic relapsing inflammatory skin disease. Studies associate an increased risk of certain cutaneous and lymphoproliferative malignancies with psoriasis.[123]

Primary cutaneous leiomyosarcomas (PCL) are rare soft tissue sarcomas displaying smooth muscle differentiation. They often present as a painful nodule over the extensor surfaces. Their etiology is relatively unknown.

The coexistence of these two distinct entities in a patient has been described.

A 58-year-old man presented with a slow growing, painless, reddish mass over his right flank since 6 months. He was a known case of plaque psoriasis since 25 years, treated only with topical steroids and emollients. There was no history of discharge, pain or previous trauma at local site. There were no systemic complaints. Cutaneous examination revealed a single, nontender, firm, exophytic tumor measuring 3.6 cm × 3.5 cm × 5 cm [Figure 1a], over right lower back, with overlying skin showing ulceration [Figure 1b]. The tumor bled on manipulation. The skin underlying the tumor mass and surrounding the growth showed well-defined erythematous plaques with silvery scales. There was no significant lymphadenopathy. Dermatofibrosarcoma protuberans and cutaneous lymphoma were considered as differentials.

Figure 1

(a) Single, firm, lobular fungating mass measuring 3.6 cm × 3.5 cm × 5 cm over right lateral aspect of lower back arising from psoriatic plaque. (b) Skin overlying the tumor showed ulceration

Routine hematological and biochemical investigations were normal.

Histopathology of excision biopsy revealed a multinodular tumor involving dermis and subcutaneous tissue, composed of fascicles of atypical spindle cells, focally in a vascular pattern. The cells exhibited hyperchromatic and pleomorphic nuclei, mitotic figures, ranging from 5 to 6/10 high power fields, including atypical forms with focal tumor necrosis [Figure 2a–c]. Immunohistochemical stain for smooth muscle actin (SMA) and H-caldesmon was strongly positive [Figure 2d and e]. It was negative for desmin, S100, MyoD1, and CD34. Final diagnosis of high-grade subcutaneous leiomyosarcoma was made. Computed tomogram (CT) scan of chest and ultrasonography of the abdomen were normal. The patient was treated with adjuvant radiotherapy for 6 months. There has been no evidence of tumor recurrence 1 year after therapy.

Figure 2

(a) Scanner view showing a cellular multinodular tumor, involving dermis and subcutis (H and E, ×10). (b) A cellular, multinodular tumor below epidermis that shows acanthosis and focal elongation of rete ridges (H and E, ×40). (c) Tumor composed of spindle-shaped cells exhibiting moderate to marked nuclear pleomorphism, with interspersed typical and atypical mitotic figures (inset) (H and E, ×100). (d) Immunohistochemical findings. Diffuse, strong H-caldesmon positivity within tumor cells in the dermis and subcutis. Overlying epidermis marked with arrows heads (diaminobenzidine, ×10). (e) Immunohistochemical findings. Diffuse, moderate smooth muscle actin (SMA) positivity within tumor cells, below epidermis (arrows heads). A predominant vascular pattern suggests the subcutaneous variant of leiomyosarcoma (diaminobenzidine, ×40)

Modest associations of psoriasis with lympho-hematopoeitic malignancy, nonmelanoma skin cancer, and melanoma have been reported.[12] The risk is highest for those with severe psoriasis and also for patients treated with PUVA, methotrexate, cyclosporine, topical tar, and biologicals.

Sarcomas are uncommonly reported in psoriasis. Rare cases of Kaposi's sarcoma in psoriatics on immunosuppressants and ACE-inhibitors have been documented.[3]

A single case of retroperitoneal leiomyosarcoma with metastasis and cicatricial pemphigoid in a psoriatic patient has been reported.[4]

PCL account for 5%–10% of all soft tissue sarcomas.[5] Ionizing irradiation, sunlight, and trauma have been associated with PCL. Cases arising in angioleiomyoma and scars have been reported.[5] PCL are classified as dermal and subcutaneous, depending on their site of origin, histopathologic features, and biological behavior [Table 1].[56] In the present case, the tumor mass replaced the entire dermis and subcutaneous tissue. It exhibited a focal vascular pattern, favoring a vascular smooth muscle origin, suggestive of the subcutaneous variant.

Table 1

Difference between dermal and subcutaneous primary cutaneous leiomyosarcomas

To the best of our knowledge, this is the first published case of PCL coexistent with psoriasis. It is difficult to speculate a plausible association between these two distinct conditions. However, any atypical changes in psoriatic plaques should validate a prompt evaluation to rule out malignant transformation.

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Conflicts of interest

There are no conflicts of interest.