Lichen planus pigmentosus (LPP) is a distinctive variant of lichen planus described for the first time in 1974. A wide range of presentations and distribution patterns have been reported, mainly presenting as dark brown hyperpigmented macules and patches, typically involving sun-exposed areas such as the face, neck, and flexural folds. It is more common in dark-skinned patients with a female predominance. Infrequently, LPP may present as a Blaschkoid distribution, with only a few cases reported in the medical literature. We report an unusual case of LPP that developed with a unilateral Blaschkoid distribution on the left side of the trunk in a 32-year-old female following weight reduction surgery.

© 2023 The Author(s). Published by S. Karger AG, Basel

Lichen planus pigmentosus (LPP) is a unique form of lichen planus (LP) with an unknown etiology [1]. The disease is characterized by irregular or oval-shaped brownish to gray-brown macules and patches on the skin that commonly involve sun-exposed areas such as the face, forehead, and neck. However, they can also affect the trunk and other intertriginous areas [2]. Blaschko’s lines are lines of normal cell development first described by Bhutani et al. [3]. Here, we report the case of a 32-year-old female with unilateral abdominal LPP who presented with a Blaschkoid distribution.

A 32-year-old woman presented to our clinic with a history of pruritic hyperpigmented macules and patches over the left lower half of the abdomen and periumbilical area for a few months. Medical history, clinical characteristics, and histopathological examination supported the diagnosis of Blaschkoid LPP. The patient had a surgical history of laparoscopic adjustable gastric band (LABG) 2 years prior to her presentation, which failed to decrease her weight. Subsequently, she underwent a one-step laparoscopic sleeve gastrectomy as a conversion procedure that successfully reduced her weight. However, a few months after the surgery, she developed multiple pigmented lesions that started over the periumbilical area and extended laterally toward the left lumbar region. Subsequently, the lesions began to become itchy and underwent further pigmentation. After reaching the optimal body weight, she underwent abdominoplasty, in which some remnants of the previously used band were found to be retained underneath the laparoscopic incision. The medical and family histories were unremarkable. There was no history of excessive sun exposure or contact with chemicals.

On clinical examination, gray to brown macules and patches arranged in a linear pattern were observed above the umbilicus, in the left periumbilical area, and in the left lower half of the abdomen, around the lumbar area; these macules and patches tended to coalesce. Additionally, a surgical scar in the left upper lumbar region was obtained from a previous laparoscopic gastrectomy. Moreover, multiple stretch marks can be seen over the lower half of the abdomen (shown in Fig. 1). Differential diagnosis of these lesions includes erythema dyschromicum perstans, post-inflammatory hyperpigmentation, idiopathic eruptive macular pigmentation, lichen striatus, and Riehl’s melanosis. Scalp, nails, and mucous membranes were not affected. Routine laboratory tests were within normal ranges, and serology for hepatitis B and C viruses was negative. Histopathological examination of the skin punch biopsy specimen showed epidermal thinning, a basket-weave horny layer, vacuolar degeneration of the basal layer, a lichenoid infiltrate (prominent basal-vacuolar degeneration), melanin incontinence, and lymphohistiocytic infiltration in the dermis. Based on the history, physical examination, laboratory results, and biopsy results, unilateral Blaschkoid LPP was diagnosed.

Hyperpigmented macules and patches distributed unilaterally over the left side of the trunk, following the lines of Blaschko.

LPP is distinct from classical LP. Differentiation between them is essential as the presentation, triggers, and treatments vary. LP commonly presents with an acute onset of pruritus, shiny and purplish papules, and plaques involving the flexor surfaces of the wrist, forearm, and legs. In addition, they may affect the nails, hair, and mucous membranes [4]. In contrast, LPP commonly presents with dark brown to gray hyperpigmented macules over sun-exposed areas [5]. The onset of the disease usually occurs in the third or fourth decade of life, with a slight female predominance [3]. Since it is caused by a delayed immune response, it has a persistent and chronic course [3].

The pathogenesis of LPP remains unknown; nevertheless, a cell-mediated immune response with CD8+ T lymphocytes along with inflammatory mediators, including tumor necrosis factor-alpha, interferon-γ, and interleukin 6, plays a major role [6]. Genetic mosaicism could also play a role in our case. T-lymphocyte migration and clonal expansion in the course of embryogenesis of the skin could express the appearance of Blaschko’s lines. The genetic mosaicism in an acquired Blaschko-linear inflammatory dermatosis could be accountable for the cutaneous antigenic mosaicism that can prompt a mosaic T-cell response based on the trigger of viral infection or drugs [1].

There are multiple differential diagnoses for Blaschkoid LPP, including erythema dyschromicum perstans, post-inflammatory hyperpigmentation, lichen striatus, linear and whorled nevoid hypermelanosis, incontinentia pigmenti, actinic LP, and Riehl’s melanosis. Since clinical differentiation is difficult, histopathological examination should be considered [7].

Although LPP is an idiopathic disease with no identifiable cause, it may appear as a lichenoid reaction to several unknown agents, including trauma, ultraviolet light, viral infections, and vaccinations [7, 8]. Seo et al. [1] reported the case of a 60-year-old male with Blaschkoid LPP and a history of gastric cancer managed subsequently with gastrectomy. Similarly, our patient underwent a sleeve gastrectomy before disease onset. However, their case presented with LPP 13 years after gastrectomy, in contrast to ours, which started only a few months after the surgery. Although their report did not relate the presentation of their case to the surgery, the correlation between the gastrectomy and LPP should be addressed. This may be attributed to alterations in the nutritional or immunological status following any surgical procedure [9]. Furthermore, there are varying degrees of inflammation and foreign body reactions following LABG procedures that may have played a role in the pathogenesis of the disease in our case [10]. Additionally, the rate of complications is higher in the one-step conversion of LABG to laparoscopic sleeve gastrectomy than in the two-step conversion, which may explain the band remnants found by the surgeon during the abdominoplasty procedure performed on our patient [11]. Similarly, a female diagnosed with Blaschkoid LPP experienced recurrence a few months after each delivery, which is thought to be triggered by pregnancy-related alterations of the immune system [12].

In 2011, Akarsu et al. [8] reported the first case of unilateral Blaschkoid LPP in the right pectoral and submammary areas. Vineet et al. [13] reported another case of unilateral Blaschkoid LPP in a 48-year-old male patient with lesions lateralizing to the right side of his body that followed the lines of Blaschko in a linear and zosteriform pattern. Polat et al. [14] reported another case of unilateral Blaschkoid LPP in a female patient who had been using levothyroxine and levetiracetam for 8 years to manage hypothyroidism and epilepsy. In contrast, our patient had no history of systemic disease and did not use any medication. Furthermore, our patient had no family history of LPP, significant sun exposure, mucosa, or nail involvement, consistent with previously reported cases [8, 13–17].

This report presents a case of a female patient with LPP that followed Blaschko’s lines. The patient had undergone LABG and a laparoscopic sleeve gastrectomy prior to the onset of her condition. Additionally, during the abdominoplasty procedure, the surgeon encountered some remnants of the previous band, which can be considered a triggering factor for this case.

Unilateral LPP with a Blaschko’s line is a unique condition. Nevertheless, this should be considered in the differential diagnosis of any macular hyperpigmentation. The appearance of LPP in our case could not be directly linked to a specific cause because of the ambiguity in the pathogenesis of the disease. However, we theorize that the presence of a foreign body at the surgical site and alterations in nutritional or immunological status due to surgical stress could have triggered the appearance of these lesions. Further research is required to better understand the nature of this disease. The CARE Checklist has been completed by the authors for this case repot, attached as an online supplementary material at www.karger.com/doi/10.1159/000529632.

Written informed consent was obtained from the patient for publication of this case report and all accompanying images. Ethical approval was not required for this case report, in accordance with local and national guidelines.

The authors have no conflicts of interest to declare.

No funding was secured for this study.

Almuntsrbellah Almudimeegh was the primary author and contributed to manuscript revising and supervision. Omar Alsuhaibani collected the clinical data and wrote the initial manuscript. Mohammed Habib and Nawaf Alkhudhayri contributed to literature review, writing, and reviewing the manuscript. All authors approved the version to be published.

All data generated or analyzed in this study are included in this article and its online supplementary material. Further inquiries can be directed to the corresponding author.

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