Annular Lupus Panniculitis on the Scalp
Lupus panniculitis, also known as lupus erythematosus profundus, is a rare and distinctive form of chronic cutaneous lupus erythematosus. It is characterized by the presence of erythema with deep subcutaneous nodules or plaques, typically observed on the face, trunk, or extremities. However, annular lupus panniculitis of the scalp is an even rarer manifestation, particularly in young individuals from East Asian or Caucasian populations. This condition presents unique clinical and histopathological features, and its diagnosis and management require careful consideration.
The case discussed here involves a 1-year-old boy who presented with progressive linear scalp hair loss that had been present for one month. Physical examination revealed an annular alopecic patch approximately 1.5 cm in width located on the right parietal and occipital areas of the scalp. The lesion was smooth, with no erythema or scales, and the patient experienced no other discomfort. His medical history and family history were unremarkable, providing no additional clues to the underlying cause of the hair loss.
Laboratory investigations were conducted to rule out systemic involvement and other potential causes. These included a complete blood count, urinalysis, liver and renal function tests, immunoglobulin (Ig) levels, erythrocyte sedimentation rate, and specific antibody determinations such as anti-double-stranded DNA, anti-Sm, anti-Ro/SSA, and anti-La/SSB. All results were normal or negative, except for the C3 component, which was slightly reduced at 0.61 g/L (normal range: 0.79–1.52 g/L), and the antinuclear antibody, which was positive at a titer of 1:80.
Histopathologic examination of the balding area provided critical diagnostic information. The biopsy revealed infiltrations of lymphocytes and plasma cells in the deep dermis and around appendages. Additionally, mucinous deposition and lymphocyte infiltrations were observed in the subcutaneous tissue. Alcian blue staining was positive, indicating the presence of mucin. Direct immunofluorescent examination, however, revealed no deposition of IgG, IgA, IgM, or C3 in the basement membrane zone. These histologic features, combined with the clinical presentation, led to the diagnosis of annular lupus panniculitis.
Annular lupus panniculitis of the scalp is a rare variant of chronic cutaneous lupus erythematosus. It typically manifests as non-scarring alopecia with minimal or no erythema. The lesions often appear as single or multiple sites distributed along Blaschko’s lines, showing linear, annular, or arc-shaped configurations. This condition is more commonly observed in young individuals, particularly those of East Asian or Caucasian descent. The histopathological findings in lupus panniculitis include a relatively sparse inflammatory infiltration, abundant mucin in the fat lobules, and a higher degree of hyaline fat degeneration. Direct immunofluorescent examinations for IgG, IgA, and IgM are usually negative in these cases, and while approximately half of the patients have positive antinuclear antibodies, few meet the criteria for systemic lupus erythematosus.
The clinical course of linear lupus panniculitis is generally reversible, with most reported cases showing significant improvement or complete hair regrowth following treatment with oral corticosteroids. Differential diagnoses for this condition include trichotillomania, tinea capitis, alopecia areata, linear morphea, and linear discoid lupus erythematosus. Accurate diagnosis is essential to guide appropriate treatment and avoid unnecessary interventions.
In the case presented, the patient was treated with a daily regimen of 8 mg oral methylprednisolone. After one month of treatment, hair regrowth was observed, and at the three-month follow-up, there were no signs of scarring or recurrence. This favorable outcome aligns with the literature, which reports that most patients with annular lupus panniculitis achieve positive responses following treatment with corticosteroids, dapsone, or hydroxychloroquine.
The management of annular lupus panniculitis requires a multidisciplinary approach, involving dermatologists, pathologists, and sometimes rheumatologists, to ensure accurate diagnosis and appropriate treatment. The use of corticosteroids remains the cornerstone of therapy, but other immunomodulatory agents may be considered in cases of inadequate response or contraindications to steroid use.
In conclusion, annular lupus panniculitis of the scalp is a rare and distinct form of chronic cutaneous lupus erythematosus. It presents with unique clinical and histopathological features, and its diagnosis requires a thorough evaluation of both clinical and laboratory findings. Early recognition and appropriate treatment are crucial to achieving favorable outcomes and preventing long-term complications. The case discussed here highlights the importance of considering lupus panniculitis in the differential diagnosis of linear or annular scalp hair loss, particularly in young patients.
doi.org/10.1097/CM9.0000000000000959
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