A Case of Multisystem Langerhans Cell Histiocytosis with Palmar Hyperkeratosis and Purpuric Nail Bands as the Initial Presentation: New Insights into An Old Disease

Dear Editor, Langerhans cell histiocytosis (LCH) is a rare disease characterized by abnormal proliferation of dendritic cells.[1] It involves multiple systems, including skin, bone, and lymph nodes. Common cutaneous presentations are erythematous papules, scaly plaques in retroauricular and seborrheic areas, and cradle caps. Palm, sole, and nail involvement are rare findings in LCH.[2,3] Nail involvement points toward a multisystem involvement, poor prognosis, and sometimes can be an initial or only manifestation of LCH. Only a few cases with nail changes in LCH have been reported in the literature.[4] However, palmar hyperkeratosis is not a recognized clinical finding in LCH, and we could not find any cases published in English literature. Our case is interesting and unique as an infant initially presented with purpuric nail and palmar hyperkeratosis, which gradually developed into a multisystemic LCH. A 9-month-old boy presented with asymptomatic reddish skin lesions on the palms, and purpuric nails for 4 months. Gradually, he developed purpuric spots on the soles and swellings on the forehead. On examination, there were multiple erythematous to skin-colored papules of size 1–3 mm on the forehead, scalp, retro-auricular area, and trunk [Figure 1a]. Multiple soft to firm swellings of 2 × 3 cm to 4 × 5 cm were present on the scalp and forehead [Figure 1b]. In addition, there were multiple hypopigmented macules on the back, scaly plaques on the scalp, and an erythematous rash on the groin and perianal cleft. His palms and soles were purplish with focal hyperkeratosis [Figure 1c]. There were longitudinal purpuric bands on all fingernails [Figure 1d]. All toenails were completely normal. A general examination revealed generalized lymphadenopathy. History and systemic examination revealed no abnormalities. The child’s height, weight, and developmental milestones were within normal age ranges. A diagnosis of multisystem LCH was considered.Figure 1: (a): Erythematous to skin-colored papules on face, forehead, and scalp mimicking seborrheic dermatitis. (b): Swelling on the forehead and scalp. (c): Focal hyperkeratosis of palms and purplish dots on soles. (d): Longitudinal purpuric bands on all fingernailsDermoscopic evaluation of erythematous skin lesions (Dermlite, non-polarized, contact dermoscopy) revealed vascular blotches, brown structureless areas, and brown dots in a pale background, suggestive of LCH [Figure 2a]. Hypopigmented and crusted lesions on the back showed white patches and central vascular blotches surrounding white rims [Figure 2b]. Palmar lesions showed similar irregular vascular blotches and brown dots along with prominent white and yellow scales [Figure 2c]. Similarly, onychoscopy revealed purplish dots and lines in a haphazard pattern and vascular blotches on the fingernails [Figure 2d].Figure 2: (a): Vascular blotches, brown structureless areas (arrows) suggestive of LCH (Dermlite, ×10 nonpolarized contact dermoscopy). (b): Hypopigmented skin lesions showing white patches and a central vascular blotch surrounded by white rims in dermoscopy (Dermlite, ×10, nonpolarized contact dermoscope). (c): Irregular vascular blotches and brown dots along with prominent white and yellow scales in palm lesions (Dermlite, ×10). (d): Longitudinal purpuric bands, vascular blotches and brown dots on all fingernails (Dermlite, ×10)Laboratory investigations revealed hypochromic microcytic anemia (hemoglobin 10 g/dL), leucocytosis (9000/μL) with normal differential count, normal erythrocyte sedimentation rate, and elevated transaminases (aspartate transaminase 542 U/L and alanine transaminase 356 U/L). The parents of the baby did not consent for a biopsy. However, classical skin lesions, dermoscopic findings, and lytic bone changes in the X-ray skull suggested a final diagnosis of LCH [Figure 3]. The patient was started on induction chemotherapy (prednisolone 40 mg/m2/day for 6 weeks and vinblastine 6 mg/m2 intravenous bolus injection weekly). The child is currently on maintenance therapy with 6-mercaptopurine and prednisolone under the oncology department.Figure 3: X-ray skull showing lytic lesions of variable sizeLCH is a rare disorder where atypical Langerhans cells infiltrate different tissues. Skin is involved in 30% to 60% of cases. Classical skin lesions include small, erythematous papules in the scalp that may resemble seborrheic dermatitis, and yellow-brown scaly papules on the trunk, flexural areas of the neck, axilla, and perineum. There may be purpura and petechiae on the skin. Palm, sole, and nail involvement in LCH is uncommon. There are only a few case reports and case series focusing on the nail changes in English literature. We could find only 18 cases of nail involvement in LCH in the literature.[1] The largest pediatric series also showed no case of nail changes.[2,3] Nail changes include hemorrhagic and pustular lesions in the nail plate, longitudinal grooving, hyperkeratosis, subungual thickening, and striate nail dystrophy. A recent report has described paronychia, discoloration, and onychorrhexis in an adult LCH case.[4] Some reports describe purpuric striations, dense deformities under nails, and nail plate loss, which is caused by the infiltration of Langerhans cells. Nail involvement in LCH indicates an unfavorable prognosis for the disease. In our case, there were classical skin findings of LCH along with erythematous to purplish plaques with scaling on both the palms and purplish dots on the soles. Similarly, all fingernails of the baby were showing longitudinal purplish bands and dots without any nail plate or nail bed changes. All the toenails were uninvolved. Table 1 describes the differentiation between LCH and seborrheic dermatitis.[2,5]Table 1: Differentiating features between Langerhans cell histiocytosis & seborrheic dermatitisDermoscopic features include widespread red-blue lacunae, reddish-purple areas and brown dots, and a central white area with peripheral telangiectasia.[2] The vascular blotches correspond to dermal haemorrhages, and brown dots or yellow structureless areas to the epidermal infiltration and necrosis by Langerhans cells.[6] The other dermoscopic features described in LCH are widespread red-blue lacunae of different sizes with a central white area, and peripheral telangiectasia (self-healing LCH),[3] and reddish-purple areas in a geographic pattern and brown dots. Other rare findings include brown structureless areas and perifollicular structureless areas (ameboid/petaloid patterns).[6] In our case, we found similar reddish-purple areas and brown dots in the dermoscopy of erythematous skin lesions. In addition, we found white areas, vascular blotches, and rims of white areas in hypopigmented lesions. In palms, the dermoscopic finding was different from the rest of the skin, in having white and yellow scales, and atypical vessels, in addition to vascular blotches and brown dots. Onychoscopy revealed prominent purplish bands of different lengths. In addition, we found irregular vascular blotches and brown dots on the nails as well as the skin, indicating a similar pathogenesis occurring in both. The only limitation of our case was that we could not perform a biopsy. There is a paucity of data on dermoscopy features of nail findings in LCH. Our case will add to the list of cases with palm, sole, and nail involvement as an initial finding with their additional dermoscopic features. Declaration of patient consent The authors certify that they have obtained all appropriate parent consent forms. In the form the their consent for the patient’s images and other clinical information to be reported in the journal. The parent understand that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Use of artificial intelligence (AI) We have not used any type of AI assistance in writing the manuscript.