CORRECT DIAGNOSIS:

Lichen Planus Pigmentosus-Inversus

DISCUSSION:

Lichen Planus Pigmentosus Inversus (LPPI) is an uncommon variant of lichen planus that primarily affects darker-skinned individuals (skin types III and IV), particularly middle-aged Indian and Middle Eastern females. While Lichen Planus Pigmentosus (LPP) typically presents as brown to violaceous or gray-brown macules, patches, or plaques in sun-exposed areas. LPPI is characterized by lesions that are limited to intertriginous areas such as the axilla, groin, and inframammary regions. The first description of this unusual variant occurred in 2001 by Pock, highlighting its occurrence in Caucasians from Central Europe. LPPI can manifest at any age but has been reported in individuals ranging from 15 to 82 years old.

LPP usually presents asymptomatically, though some patients may experience mild pruritus or a burning sensation. The lesions can evolve from macules to diffuse or reticulate pigmentation and typically do not involve hair, nails, mucosal surfaces, or palmoplantar areas. The course is chronic and progressive, with remissions and exacerbations, and can last from six months to three years. LPPI is associated with various conditions, including hepatitis C, diabetes mellitus, autoimmune disorders (such as hypothyroidism and vitiligo), hyperlipidemia, chronic urticaria, and tuberculosis.

The pathogenesis of LPPI is thought to involve T lymphocyte-mediated cytotoxic activity against basal keratinocytes, with potential triggers including external mechanical stimuli (e.g., friction from tight clothing) and the use of certain topical products (such as mustard oil and henna). Recent reports have also suggested associations with radiotherapy, paraneoplastic syndromes, and COVID-19 vaccination.

Diagnosis of LPPI is primarily clinical, based on the characteristic appearance of the lesions and patient history. A thorough evaluation for associated conditions is also critical. A skin biopsy may be performed to confirm the diagnosis and rule out other dermatological conditions. Histopathological examination typically reveals key features such as a band-like infiltrate of lymphocytes in the upper dermis, vacuolar degeneration at the epidermal-dermal junction, and pigmentary incontinence due to melanin leakage, supporting a diagnosis of LPPI.

In this case, our patient’s lesions, which developed after a hospitalization for a urinary tract infection complicated by sepsis, reflect the common trigger of external mechanical stimuli in LPPI, especially given their location in intertriginous areas. Given the associations of LPPI with systemic conditions like diabetes and autoimmune disorders, the patient’s medical history raises the possibility of a multifactorial etiology. Therefore, a comprehensive clinical evaluation remains essential for managing his skin condition and monitoring for potential complications related to underlying systemic diseases. 

TREATMENT:

CONCLUSION:

LPPI is a distinctive variant of lichen planus that primarily affects darker-skinned individuals, particularly middle-aged Indian and Middle Eastern females. Clinically, it presents as asymptomatic brown to violaceous macules and plaques localized to intertriginous areas, such as the axilla, groin, and inframammary folds, sparing sun-exposed skin. The association with various systemic conditions, including hepatitis C and autoimmune disorders, underscores the importance of a comprehensive clinical evaluation.

The chronic and progressive nature of LPPI, characterized by remissions and exacerbations, complicates its management and necessitates careful monitoring. Understanding the potential triggers—such as friction, certain topical agents, and recent reports linking LPPI to external stimuli—can aid in patient education and management. Overall, LPPI represents a unique clinical entity that requires a nuanced approach to diagnosis and treatment, with ongoing research necessary to elucidate its underlying pathophysiology and optimal management strategies.

REFERENCES:

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