Squamous Cell Carcinoma Arising from Hypertrophic Lichen Planus

Lichen planus is not a common premalignant condition; a study showed only 8 SCC developing in 2071 patients of lichen planus followed up for over 9.9 years.[1] LPH and oral lichen planus are two variants which have a higher risk of malignant transformation. Till December 2015, 38 cases of SCC developing in LPH have been reported.[2] SCC arising from LPH is most commonly seen on the lower limbs, similar to this case, but it has also been reported at other sites such as the glans penis.[3,4] The average age of presentation is 61.4 years in women and 51.3 years in men,[2] however, it can also occur in young patients.[3,5] Previously, X‐ray and arsenic treatment were considered to be risk factors for the development of SCC in LPH,[3] however, another review did not reveal any significant predisposing factors such as personal history of malignancy, use of phototherapy, Sir, A 60‐year‐old lady presented with multiple violaceous plaques, nodules, and a proliferating growth on the right knee. She had multiple oval and linear, 7 × 4 cm to 8 × 3 cm, hypertrophic verrucous plaques and nodules with a violaceous rim and hypopigmented center. These plaques and nodules were present on bilateral forearms, left palm, left ankle, and right knee [Figure 1] for the last 5 years, and were associated with slight itching. In the last 6 months, the plaque on the right knee showed a gradually progressing circular nodule, 5 × 5 cm, with a moist surface and indurated base and bled on slight touch [Figure 2]. Regional lymphadenopathy was absent. There was no systemic complaint. Biopsy from the hypertrophic violaceous plaque on the knee showed hyperkeratosis, irregular epidermal acanthosis with saw‐tooth type rete pegs, and focal basal layer vacuolar degeneration. The superficial dermis and dermoepidermal junction showed lymphohistiocytes in a band‐like pattern suggestive of hypertrophic lichen planus (LPH) [Figure 3]. Biopsy from the proliferating nodule did not have any epidermis or dermis. Sections showed sheets of proliferating keratinocytes and tiny squamous pearls with mild pleomorphism of keratinocytes suggestive of well‐differentiated squamous cell carcinoma (SCC) [Figure 4]. Routine investigations, chest X‐ray, human immunodeficiency virus (HIV), anti‐hepatitis C virus (HCV), HBSAg, and abdominal ultrasound study were within normal limits. Magnetic resonance imaging (MRI) showed two lymphnodes of size 1 cm in the right inguinal region which on fine needle aspiration showed reactive lymphadenitis. The patient