Dermatology: Practical and Conceptual Dermatology Practical & Conceptual Letter | Dermatol Pract Concept. 2021; 11(3):e2021047 1 Unilateral Pompholyx in a Patient of Anterior Horn Disease: An Unusual Presentation Biswanath Behera1, Rashmi Kumari2, Debasis Gochhait3 , Pavithra Ayyanar4 1 Department of Dermatology, and Venereology, AIIMS, Bhubaneswar, India. 2 Department of Dermatology, Venereology and Leprology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India 3 Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India 4 Department of Pathology, AIIMS, Bhubaneswar, India. Key words: Dermoscopy, eczema, dyshidrotic, pompholyx Citation: Behera B, Kumari R, Gochhait D, Ayyanar P. Unilateral pompholyx in a patient of anterior horn disease: an unusual presentation. Dermatol Pract Concept. 2021; 11(3):e2021047. DOI: https://doi.org/10.5826/dpc.1103a47 Accepted: January 3, 2021; Published: July 8, 2021 Copyright: ©2021 Behera et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License BY- NC-4.0, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited Funding: None. Competing interests: The authors have no conflict of interest to disclose. Authorship: All authors have contributed significantly to this publication. Corresponding author: Dr. Rashmi Kumari, M.D., Associate Professor, Dept. of Dermatology, Venereology and Leprology, JIPMER, Puducherry, Pin-605006. Phone no- 09489692199, Email- rashmi.sreerag@gmail.com Introduction Pompholyx is a type of eczematous dermatitis, presenting deep-seated vesicles and bullae (blisters) over the bilateral acral skin. Isolated palmar involvement is the most common (70%), followed by palmoplantar (20%), and isolated plan- tar involvement (10%). Diagnosis is rarely difficult when it presents in the classical form, although, at times, dermatoses such as dyshidrosiform bullous pemphigoid, epidermolysis bullosa aquisita, and in the pediatric population, scabies and acropustulosis need to be ruled out. The unilateral localiza- tion of pompholyx is an unusual presentation [1]. Case Presentation A 25-year-old male had a 2-months history of itchy lesions over the right hand, associated with increased sweating. The patient was a known case of anterior horn disease and had right upper limb paresis. He denied any personal or fam- ily history of atopy, prior history of contact dermatitis, or adverse drug reaction. Cutaneous examination showed mul- tiple deep-seated vesicles over the palmar, lateral, and dorsal areas of the right medial 4 digits, with areas showing desqua- mation (Figure 1). The contralateral hand was within normal limits. Upon nonpolarized dermoscopy only featureless areas (Figure 2) were evident. Therefore, a differential diagnosis of pompholyx and tinea manuum was considered. Histological analysis showed acanthotic epidermis, spongiosis, spongiotic vesicles, and upper perivascular mild lymphocytic infiltration (Figure 3). Staining for fungus and bacteria detection was negative. The diagnosis of pompholyx was made, and the patient was treated with topical clobetasol 0.05% cream twice daily, for 15 days. Pompholyx can be associated with or present manifes- tations of various dermatoses such as atopic dermatitis, contact dermatitis, adverse drug eruption, Id reactions, and HIV infection [1]. Unilateral pompholyx can be challenging to diagnose and needs to be distinguished from tinea pedis, 2 Letter | Dermatol Pract Concept. 2021; 11(3):e2021047 bullous impetigo, herpes zoster, fixed drug eruption, and friction blister as all of them can produce itchy vesiculobul- lous lesions [1].Pompholyx is known to be associated with hyperhidrosis and factors that promote an increase in sweat- ing. It is exacerbated by hot and humid environments, stress, smoking, and the use of occlusive gloves. The association of pompholyx with increased sweating is further supported by the acral location of pompholyx, which has the highest con- centration of sweat glands, increased perspiration volume in patients with pompholyx, and iontophoresis as a modality of therapy [1].In our case, the unilateral localization of pompho- lyx was associated with an ipsilateral upper limb paresis and anterior horn disease. A similar case of unilateral pompholyx has been reported in association with amyotrophic lateral sclerosis (ALS). The authors attributed the disease-associated sympathetic overactivity to be responsible for the increased sweating and development of pompholyx [2]. Various cuta- Figure 1. (A) and (B) Multiple deep-seated vesicles (arrows) over the palmar, lateral, and dorsal aspect of right medial four digits, along with areas of desquamation. The contralateral hand is within normal limits. Figure 2. Dermoscopy under nonpolarized mode showing featureless areas. Figure 3. Histology showing the acanthotic epidermis, spongiosis, spongiotic vesicles, and upper perivascular mild lymphocytic infiltration (H&E, x100). Letter | Dermatol Pract Concept. 2021; 11(3):e2021047 3 neous changes have been described in the paralytic limb, such as edema, reduced minimum erythema dose, increased tanning, and reduced sebum secretion. In the index case, the altered autonomic nervous function is possibly responsible for the unilateral localization of the pompholyx, as evidenced by increased sweating [3]. The sympathetic system’s role is further backed up by the resolution of the right-sided eczema and hyperhidrosis with the persistence of contralateral hyper- hidrosis and eczema, following right-sided sympathectomy [4]. It is postulated that the high concentration of cytokines and proteases detected in the sweat stimulate inflammation and spongiosis, leading to the development of pompholyx [4]. Conclusion In conclusion, we reported a rare case of unilateral pompho- lyx in a patient with anterior horn disease that was localized to the ipsilateral side of the upper limb paresis. References 1. Guillet MH, Wierzbicka E, Guillet S, Dagregorio G, Guillet G. A 3-year causative study of pompholyx in 120 patients. Arch Dermatol. 2007;143(12):1504-1508. DOI: 10.1001/arch- derm.143.12.1504 2. 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