A 2-month-old male infant presented with a subcutaneous mass on the left middle finger; the mass had been present since birth. This was treated with local excision, and there has been no recurrence. Histology revealed the typical features of a fibrous hamartoma. Cytogenetic studies revealed a reciprocal translocation, t(2;3)(q31;q21), as the sole abnormality. To our knowledge, this is the first report of the cytogenetic findings in fibrous hamartoma, and it suggests that this lesion represents a benign neoplasm.

A case of recurrent and synchronous fibrous hamartoma of infancy.Pediatr Surg Int. 2005 Feb;21(2):119-20. Epub 2005 Jan 11.

We retrospectively reviewed the chart of a patient with recurrent fibrous hamartoma of infancy (FHI). This lesion presented as a gradually enlarging mass on the child's buttock. The child, a 6-month-old male, was followed up, and at 19 months of age the mass was excised. Eighteen months after the initial operation, a local recurrence was noticed. Forty-one months after the initial operation, reexcision was performed. Both masses demonstrated the characteristic features of FHI, which should be considered in the differential diagnosis of subcutaneous mass in young children.

A clinicopathologic study of 45 pediatric soft tissue tumors with an admixture of adipose tissue and fibroblastic elements, and a proposal for classification as lipofibromatosis.Am J Surg Pathol. 2000 Nov;24(11):1491-500.

The tumor described here as lipofibromatosis is a rare pediatric neoplasm that has been variously interpreted as a type of infantile or juvenile fibromatosis, a variant of fibrous hamartoma of infancy, and a fibrosing lipoblastoma. This report details the clinicopathologic features associated with 45 cases of this soft tissue entity. The study group consisted of 32 males, 12 females, and one person of unstated gender. The patients presented with a soft tissue mass (range, 1-7 cm) involving the hand (n = 18), arm (n = 8), leg (n = 7), foot (n = 6), trunk (n = 5), or head (n = 1). Eight tumors were evident at birth. The individuals ranged in age from 11 days to 12 years (median age, 1 yr) at the time of initial biopsy or resection. Microscopic examination revealed abundant adipose tissue with a spindled fibroblastic element that chiefly involved the septa of fat and skeletal muscle. The process generally did not cause extensive architectural effacement of fat as is common with conventional fibromatoses, and it did not have a primitive nodular fibromyxoid component as is characteristic of fibrous hamartoma of infancy. The fibroblastic element exhibited focal fascicular growth and typically had limited mitotic activity (< or = 1 mitosis/ 10 high-power fields) and cytologic atypia. Oftentimes, small collections of univacuolated cells were present at the interface between some of the fibroblastic fascicles and the mature adipocytes. The tumors entrapped vessels (n = 45), nerves (n = 44), skin adnexa (n = 16), and skeletal muscle (n = 18). Focal immunoreactivity was present in some tumors for CD99, CD34, alpha-smooth muscle actin, BCL-2, and less frequently, S-100 protein, muscle actin (HUC 1-1), and EMA. However, no reactivity was detected for desmin (D33 and D-ER- 1 clones), keratins, or CD57. Follow-up data were available for 25 individuals (median follow-up period, 6 yrs 7 mos) with regrowth of the tumor or persistent disease documented in 17 (72%). The following events were more common in the group with recurrent or persistent disease: congenital onset, male sex, hand and foot location, incomplete excision, and mitotic activity in the fibroblastic element. Although it is likely this tumor comprises part of the spectrum of what has been referred to in the literature as infantile/juvenile fibromatosis, its clinicopathologic features and, in particular, its distinctive tendency to contain fat as an integral component, warrant separate classification as a "lipofibromatosis."