Cutaneous Fibrous Histiocytoma in an 8-year-old: A Rare Paediatric Case from India

Cutaneous fibrous histiocytoma (CFH), also termed dermatofibroma, is a benign dermal neoplasm composed of fibroblastic and histiocytic cells. It predominantly affects adults between 20 and 40 years, with a female preponderance of 2:1.1,2 Clinical presentation of CFH is a firm, dome-shaped or flat nodule, usually of size <1 cm, most commonly on the lower limbs. Paediatric cases, particularly in children under 10 years, are exceptionally rare, with fewer than 15 cases reported from India.3 In children, CFH may present at atypical sites, such as the upper limbs, trunk or even the face, and may lack classical signs such as the dimple sign, complicating clinical diagnosis.3,4 An 8-year-old boy presented with a solitary, painless nodule on the left forearm of one year duration, which had gradually increased in size. History of trauma, insect bite, vaccination or systemic illness was negative. The child’s growth and developmental milestones were normal. On examination, the lesion was well-circumscribed, firm, mobile, non-tender and 1.2 cm × 1.2 cm in size. The overlying skin was unremarkable; no pigmentation, scaling or ulceration was seen. The dimple sign was negative, and no regional lymphadenopathy was noted. Clinical differentials included juvenile xanthogranuloma, pilomatricoma, trichilemmoma, steatocystoma and dermatofibrosarcoma protuberans (DFSP). CFH was not initially considered due to its rarity in this age group. The lesion was excised under local anaesthesia. Gross examination revealed a firm, grey-white nodule. Histopathological analysis showed hyperkeratosis with flattening of the rete ridges. The dermis contained spindle-shaped fibroblasts arranged in a storiform pattern, interspersed with foamy histiocytes, multinucleated giant cells and hyalinised collagen Figure 1. The lesion was well-circumscribed and unencapsulated, extending superficially to skeletal muscle. Evidence of mitosis, atypia or necrosis, consistent with CFH, was absent.Figure 1: (a) Photomicrograph showing hyperkeratotic epidermis (A) with flattening of the rete ridges (B) (Hematoxylin and eosin stain, ×100). (b) Dermis showing foamy histiocytes (A), spindle-shaped fibroblasts arranged in a storiform pattern (B), and a multinucleated giant cell (C) (Hematoxylin and eosin stain, ×400)Immunohistochemistry revealed strong CD68 positivity Figure 2, confirming histiocytic lineage, whereas factor XIIIa, vimentin and CD34 were negative, effectively excluding DFSP.5,6 Factor XIIIa negativity is uncommon but has been reported in paediatric CFH, emphasising that diagnosis should rely primarily on morphologic features, with immunomarkers used to support the interpretation rather than solely define it.7Figure 2: Diffused cytoplasmic and membranic staining by CD 68 on immunohistochemistryCFH is a benign dermal tumour of mixed fibroblastic and histiocytic origin. Although frequently encountered in adults, paediatric cases are uncommon and often present diagnostic challenges due to atypical location, absence of pigmentation or negative dimple sign.3,4 Paediatric lesions may occur on the upper limbs or trunk, unlike adult lesions, which predominantly affect the lower extremities. Histopathology remains the gold standard for diagnosis, demonstrating a characteristic storiform arrangement of spindle cells interspersed with histiocytes, giant cells and collagen trapping.2,4 Immunohistochemistry helps differentiate CFH from mimickers such as DFSP, which demonstrates strong CD34 positivity but lacks histiocytic markers.5,6 Paediatric CFH may occasionally show atypical immunoprofiles, as in our case, where factor XIIIa and vimentin were negative but CD68 was positive.7 Differential diagnoses include juvenile xanthogranuloma (lipid-laden histiocytes and Touton giant cells), pilomatricoma (ghost cells and calcification) and DFSP (infiltrative spindle cells with mitotic activity). Correct histopathological evaluation prevents misdiagnosis, unnecessary wide excisions and overtreatment. Surgical excision with clear margins remains curative, with recurrences being rare.2,5 This case contributes to the limited paediatric CFH literature from India, highlighting that the lesion can present at atypical locations with classic signs being negative. Awareness amongst clinicians and pathologists is essential to ensure correct diagnosis and management. Authors’ contributions PS and MG: Concept, design, definition of intellectual content, literature search, clinical studies, manuscript preparation, manuscript editing and manuscript review. SK: Concept, design, literature search, clinical studies, manuscript preparation, manuscript editing and manuscript review. VC: Concept, design, literature search, manuscript preparation, manuscript editing and manuscript review. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.