Psoriatic Arthritis with Acral Lentiginous Melanoma: Role for Methotrexate?
A 50-year-old male with psoriatic arthritis since 20 years on methotrexate, since 12 years on and off with a cumulative dose of 1080 mg, developed an asymptomatic black lesion over his right sole near the instep since 2 years which was gradually increasing in size over last 6 months. No h/o bleeding or ulceration of the lesion. He was a known hypertensive and diabetic. On examination, patient had pallor and right inguinal lymph nodes were enlarged and firm in consistency.\nExamination of right sole revealed a hyperpigmented plaque of 3 × 5 cm with surface and border irregularities []. There was no scaling, ulceration, bleeding or induration. Multiple hyperpigmented macules were present over both soles varying in size from 0.3 × 0.3 cm to 1 × 1 cm. There were also multiple discrete and confluent erythematous papules and plaques over thighs, forearm, arms and trunk. Scalp showed scaly plaques. There was subungual hyperkeratosis in all nails. Oral mucosa revealed a black pigmentation.\nExamination of musculoskeletal system revealed swan neck deformity of left lateral 3 fingers and right 4 fingers and Boutennaire deformity of left index finger, proximal dislocation of middle toes bilaterally. There was swelling and deformity of both knee joints. With all these findings, we made a provisional diagnosis of psoriasis with mutilating type of psoriatic arthropathy with acral lentiginous melanoma.\nInvestigations showed an ESR of 130, rheumatoid factor was negative, but C-reactive protein was positive. SGOT was slightly elevated and cytology from the knee joint aspiration was sterile and predominantly composed of neutrophils. Excision biopsy of the blackish plaque revealed epidermis with junctional activity and nests of cells of melanoma cells containing melanin in dermis consistent with malignant melanoma Clark level-III with no involvement of the circumferential deep margin [Figures and ]. Another biopsy from the smaller hyperpigmented macule on the sole was unremarkable. Lymph node biopsy from right inguinal lymph node showed only reactive hyperplasia.\nLesion was completely excised with a margin of 2 cm and chemotherapy with Inj. Dacarbazine 300 mg infusion for 4 days every month was given for 6 months. Lesions completely subsided [] and there were no signs of relapse or metastases till date.