Spindle cell xanthogranuloma is a rare variant form of juvenile xanthogranuloma. It presents with a well demarcated nodule composed predominantly of spindle-shaped histiocytes in a storiform arrangement. Usually, SCXG develops in young adult and it is clinically characterized by a yellow to brownish papule. It commonly affects head, neck, and upper portion of trunk. Less common sites include extremities.2
Twelve cases of solitary spindle cell xanthogranuloma were described in 1995 by Zelger et al.3 Thereafter, only a handful cases of solitary spindle cell xanthogranuloma have been reported, however, no congenital cases have been previously reported. This is the first case of congenital solitary spindle cell xanthogranuloma.
The main differential diagnosis with dermatofibroma. According to Zelger et al,3 7 of their 12 cases had originally been misdiagnosed as dermatofibroma/benign fibrous histiocytoma. Clinically, SCXG can mimic dermatofibroma (DF), and histologically both disease can show a storiform arrangement of spindle cells. However, dermatofibroma typically develops on the legs of middle-aged women.
Several histopathological findings such as marked epidermal hyperplasia including increased basal pigmentation, elongation of rete ridge associated with peripheral sclerotic collagen bundles, favor the diagnosis of dermatofibroma rather than SCXG. In the case of dermatofibroma, macrophages and multinucleated giant cells can be seen, but not as predominant as in SCXG. Immunohistochemical stains stain for macrophages such as CD 68 and Mac 387, are usually negative in dermatofibroma but are strongly positive in SCXG. Furthermore, in dermatofibromas, Factor XIIIa stain is usually positive; and negative in SCXG. Factor XIIIa stain was negative in our case.
Progressive nodular histiocytosis should also be considered in the differential diagnosis, It shares common features such as the presence of Touton type multinucleated giant cells and a, storiform arrangement of spindle cells. Unlike SCXG, progressive nodular histiocytosis usually develops in older adults and shows a disseminated distribution.
In our case, numerous eosinophils were noted in the deep dermis, which is an atypical finding in SCXG.
We will monitor this patient to detect any progression or change of the lesion, considering the possibility of progression of SCXG to progressvie nodular histiochytosis.
In conclusion, SCXG is a very rare variant of juvenile xanthogranuloma, and clinician should consider the possibility SCXG in the differential diagnosis of dermatofibroma, progressive nodular histiocytosis, and JXG, because both clinically and histologically SCXG can mimic these diseases.
1. Zelger BW, Sidoroff A, Orchard G, et al.. Non-Langerhans cell histocytoses. A new unifying concept. Am J Dermatopathol. 1996; 18:490–504.
2. DeStafeno JJ, Carlson JA, Meyer DR. Solitary spindle-cell xanthogranuloma of the eyelid. Opthalmology. 2002;109:258–261.
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3. Zelger BW, Staudacher C, Orchard G, et al.. Solitary and generalized variants of spindle cell xanthogranuloma (progressive nodular histiocytosis). Histopathology. 1995;27:11–19.