Multiple yellow-red papules on the cheeks of an infant
A 7-month-old boy was presented by his parents with multiple yellow-red papules on both cheeks (Fig. 1) and some disseminated brownish papules on the sides of the neck. The lesions were asymptomatic. They had appeared for the first time 3 months previously on the face and had subsequently increased in number. There was no response to various treatments, including clindamycin solution, corticosteroids, and immunomodulators administered topically.
Multiple yellow-red papules on both cheeks
Histology from a papular lesion on the neck revealed an infiltrate in the papillary dermis with large, pleomorphic, epithelioid histiocytic cells with amphophilic cytoplasm and prominent nucleoli (Figs. 2A-2D). Mitoses were absent. Immunohistochemical staining revealed cells in the infiltrate to be positive for both CD68 and S-100 (Figs. 3A and B) .
Fig. 2A and B
Infiltrate in the papillary dermis with lymphocytes and histiocytes.
Fig. 2C and D
Large, pleomorphic, epitheloid histiocytes in the dermal infiltrate
Epitheloid cells in the dermis stain positive with CD68.
Unusual positivity of the cells in the dermis with S100.
What is your diagnosis?
Clinical and histopathologic features are those of benign cephalic histiocytosis (BCH). The positivity with S-100, however, is unusual.
Benign cephalic histiocytosis (BCH) is a rare, benign, self-healing papular eruption that affects mainly children. It consists of small papules on the face and upper trunk. The histiocytes in the infiltrate are not Langerhans cells, which distinguishes this disorder from Langerhans cell histiocytosis. BCH has no associated involvement of internal organs. The little patient presented here was examined thoroughly by pediatricians and pediatric neurologists with no abnormal results. A follow-up showed that the eruption had remained stable but lesions were getting paler.
The literature on BCH is rather poor and consists mostly of isolated case reports of children of different ethnic groups. There are 42 cases reported worldwide. [1,2] Patients affected by BCH are infants. Typical lesions are red-brown papules on the face, neck, and shoulders. The average age of onset is 15 months, with 45% occurring in infants younger than 6 months.  The eruption regresses spontaneously in most cases, and complete regression occurs in an average of 50 months. 
On histology, an infiltrate in the upper dermis consists of densly packed macrophages with regularly shaped nuclei and eosinophilic cytoplasm. The cells are usually positive with CD68 and FXIIIa, but negative with S-100 and CD1a staining.
Several authors have suggested that BCH belongs to the spectrum of juvenile xanthogranuloma (JXG). [5,6] Overlapping features with generalized eruptive histiocytosis, progressive nodular histiocytosis, papular xanthomas, and multiple xanthogranulomas have been described. On occasion, distinction of BCH from a Langerhans-cell histiocytosis may be difficult on clinical grounds alone. 
In the case presented here, S-100 positivity of cells in the infiltrate initially called into question the diagnosis of BCH, but the rest of clinical and histological findings were typical. Moreover, cells staining faintly positive with S-100 have been described in two cases of BCH reported previously. [3,4]
The term “intermediate cell histiocytosis” has been used to designate cases where an infiltrate of mononuclear cells with foamy cytoplasm and giant cells are positive for both, CD68 and S100. It has been proposed that these cases represent disorders of macrophages, variants of xanthogranuloma or just reactive processes after an infection. 
In a recent article, Yamamoto et al. reported the first case of an S-100 positive juvenile xanthogranuloma. They suggested that S-100 positivity is not always a reliable marker for differentiating JXG from Langerhans cell histiocytosis and they speculated that S-100 positivity in JXG may be seen at an early stage of the disease.  Accordingly, BCH could represent an early manifestation of JXG which offers an explanation for the S-100 positivity of cells in the infiltrate of our case.
Considering the age of patients with BCH, the clinical and histopathological overlap of the disease with the more life-threatening Langerhans cell histiocytosis, collection of data on all histiocytoses of infancy and a thorough study of clinicopathological features is needed.
A 7-month-old boy with multiple yellow-red papules on both cheeks and some disseminated brownish papules on the sides of the neck is presented as a quiz. A diagnosis of benign cephalic histiocytosis was made based on clinical and histopathologic features. The literature on this rarely diagnosed condition is reviewed.
Aikaterini Patsatsi, Dimitrios Kalabalikis, Myrto-Georgia Trakatelli, Stylianos Charalabidis, and Dimitrios Sotiriadis are from the Second Dermatologic Clinic, Medical School, Aristotle University, Papageorgiou Hospital, Thessaloniki, Greece. Ioannis Efstratiou works at the Department of Pathology, Papageorgiou Hospital, Thessaloniki, Greece. This article was reviewed by Almut Böer-Auer, M.D., and Valentina Dimitrova, M.D. Contact corresponding author via email: firstname.lastname@example.org .
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