Successful Treatment of Non-Langerhans Cell Histiocytosis With Topical Rapamycin in Two Pediatric Cases

Abstract

Non-Langerhans cell histiocytosis (non-LCH) is a group of diseases characterized by the proliferation of histiocytes in tissues that is excluded from the diagnostic criteria for LCH. Juvenile xanthogranuloma (JXG) and benign cephalic histiocytosis (BCH) are the most common types of cutaneous non-LCH. These two diseases share similarities in both clinical and histological features, therefore, they can be difficult to differentiate. Thorough physical, dermoscopic, and histopathological examinations are required to distinguish between JXG and BCH. We hereby present two rare cases of non-LCH in pediatric patients, presented with JXG and BCH. The dermoscopic examination of both cases showed a setting-sun appearance, while the histopathological examination revealed Touton giant cells in the JXG case, and massive lymphocyte infiltration in the BCH case. Both patients were treated with 1% topical rapamycin in a split-side comparison for the first 12 weeks, followed by applications on both sides for a total duration of 24 weeks. As a result, there was a significant reduction in the size of the lesion, leading to patient's satisfaction. Rapamycin is an immunosuppressive agent with antineoplastic activity. Rapamycin can be used as an alternative non-invasive topical treatment option for JXG and BCH. However, long-term observations are required to assess its effectiveness and side effects.

Keywords: benign cephalic histiocytosis; dermoscopy examination; histopathological examination; juvenile xanthogranuloma; non-Langerhans cell histiocytosis.

Figure 1

Comparison of pre-treatment and post-treatment features in Case 1. Tan-Orange papules and plaques on the face (A,B,C) before treatment. The patient was treated with topical 1% rapamycin ointment twice daily for 24 weeks. Most of the skin lesions on the face flattened and faded (D,E,F).

Figure 2

Supporting examination of Case 1. (A) Dermoscopic examination revealed a brownish-yellow hue resembling a “setting-sun appearance”. (B) Histopathological features of the skin lesions: (1) Infiltration of lymphocytes, foam cells, and histiocytes in the upper dermis. (2) Histiocytes forming Touton giant cells (red circle). (C) Immunohistochemistry analysis: (1) CD68 positive. (2) S100 positive in Langerhans cell and nerve cell. (3) CD1a negative.

Figure 3

Comparison of pre-treatment and post-treatment features in Case 2. Multiple tan-Orange nodules on the scalp (A-C) before treatment. The patient was treated with topical 1% rapamycin cream twice daily for 24 weeks. Most of the skin lesions on the scalp decrease in size and faded (D-F).

Figure 4

Supporting examination of Case 2. (A) Dermoscopic examination revealed brownish-yellow structureless center with a pale erythematous halo lesion was observed, indicating a “setting-sun appearance”. (B) Histopathological features of the skin lesions fibrocollagenous connective tissue on the dermis with massive histiocyte infiltration. (C) Immunohistochemistry analysis: (1) CD68 positive, (2) S100 weak positive for S100. (3) CD1a negative.