Generalised Benign Acanthosis Nigricans with Lichen Planus Pigmentosus in an Adult

Sir, Acanthosis nigricans (AN) is a skin disorder characterised by skin hyperpigmentation and thickening. Lichen planus pigmentosus (LPP) presents as asymptomatic slaty-grey pigmentation. In our case, LPP co-existed with the generalised form of acanthosis nigricans along with tripe palms, especially without any evidence of internal malignancy and is being reported for its rarity. A 55-year-old female presented with generalised hyperpigmentation for the past 20 months. It started from the neck and buttock regions and progressed to cover the whole body within 2 months, sparing her palms and soles. It was associated with pruritus. After 2–3 months, she developed generalised thickening of the skin except for her face, along with rugosity on her palms and soles. Her oral and genital mucosae were also involved. The patient had a past history of bullous pemphigoid and angioedema with no endocrinological abnormalities. She underwent a hysterectomy at the age of 35 years for adenomyosis. General and systemic examination were normal. On cutaneous examination, the patient had generalised greyish pigmentation, except for her palms and soles [Figure 1]. Symmetric, hypertrophic, papillomatous, velvety, hyperpigmented plaques were seen all over her body except her face [Figure 2]. Tripe palms along with pigmentation over her genital and oral mucosa were seen [Figure 3]. Laboratory findings revealed a haemoglobin of 10.6 gm/dL, an ESR of 69 mm/h and an increased eosinophil count (38%). The fasting blood glucose level was 74 mg/dL. Ultrasonography (USG) whole abdomen and chest X-ray were normal. Patch testing revealed positive reactions to parthenium, balsam of Peru and epoxy resin. Allergy to dust particles was found on the allergy test. Upper GI endoscopy showed mild gastritis. Biopsy taken from a skin lesion on the forearm revealed hyperkeratosis, papillomatosis and only slight irregular acanthosis, consistent with AN [Figure 4], whereas that from the face showed hyperkeratosis, lichenoid infiltration, vacuolar degeneration, melanin incontinence and dermal melanophages, consistent with LPP [Figure 5]. The patient was initially treated with isotretinoin 20 mg daily for 2 months, followed by acitretin 25 mg daily for 2 months. Due to a lack of response, she was given prednisolone 30 mg daily for 1 month. Finally, she was treated with cyclosporin 150 mg daily for 1 month. A minimal response was noted.Figure 1: Greyish pigmentation over the faceFigure 2: Symmetric, hypertrophic, papillomatous, velvety, hyperpigmented plaque over bilateral forearm and dorsum of the handFigure 3: (a) Tripe palm. (b) Oral mucosal pigmentationFigure 4: Biopsy from the forearm showing hyperkeratosis, papillomatosis with the collection of eosinophils with slight irregular acanthosis, (a) H and E 4 ×. (b) H and E 10 ×Figure 5: Biopsy from the face showing hyperkeratosis, lichenoid infiltrate, vacuolar degeneration, melanin incontinence, dermal melanophages (a) H and E 4 ×. (b) H and E 10 ×The malignant form of AN is associated with adenocarcinoma of the gastrointestinal tract, lung and breast. The age of onset is more than 40 years. Sudden onset, rapid progression, mucosal involvement and tripe palms are clinical indicators of malignancy. Other causes of AN are autosomal dominant inheritance, obesity, insulin-resistant states and endocrinopathies. Very few such cases have been reported where generalised AN is not associated with internal malignancy. Amongst them, one case reported from West Bengal was of a 1-year-old female child who developed generalised AN without any evidence of internal malignancy or endocrine disorder. Another case was reported in which a 1-year-old female child born of a non-consanguineous marriage with normal growth and developmental milestones presented with progressive generalised darkening and thickening of the skin without any internal malignancy. LPP is a chronic, relapsing and remitting dyspigmentation of the skin, seen in young to middle-aged individuals. In adults, the differential diagnosis includes erythema dyschromicum perstans. LPP has been reported to be associated with scarring alopecia and circulating antinuclear antibodies[1], frontal fibrosing alopecia,[2] acrokeratosis of Bazex and head and neck carcinoma (paraneoplastic LPP)[3], hepatitis C infection[4] and nephrotic syndrome[5] but never with benign generalised acanthosis nigricans to the best of our knowledge. The diagnoses of Addisonian pigmentation, Cushing's disease and hyperthyroidism were excluded by examining hormonal profiles. Vitamin B12 deficiency and hemochromatosis were ruled out by examining vitamin B12 and serum ferritin levels, respectively. Generalised fixed drug eruption and drug-induced pigmentation were excluded as no offending drugs were found. Pigmented contact dermatitis was excluded through patch testing. In conclusion, no malignancy has been detected until now in our case, whereas in most cases, the generalised form is related to malignancy in adults. Also, there are no reported cases in the literature showing an association between LPP and generalised benign form of AN. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.