“A Three Year-old Girl With An
Enlarging Shoulder Mass
California Tumor Tissue Registry’s
Case of the Month
CTTR COTM Vol. 17:3
December, 2014
www.cttr.org
A 3 year old girl presented with a solitary, painless, rapidly growing shoulder mass. On
physical exam it was mobile, non-tender and irregular. The overlying skin did not show
any changes. Neither the patient nor her family had any pertinent past medical history.
The excised specimen was 5.5 x 5.0 x 3.0 cm, tan-yellow, poorly circumscribed and
predominantly comprised of fibrofatty tissue.
Microscopically the nodule involved the subcutis (Fig. 1) and consisted of an admixture
of mature adipose tissue, intersecting trabeculae of fibrous tissue with mature spindleshaped cells and collagen bundles (Figs. 2, 3). It also showed loosely textured
“organoid” areas of myxoid matrix with densely packed round to spindle shaped cells
(Figs. 2-4). Neither muscular elements nor cellular atypia were seen.
Diagnosis: Fibrous Hamartoma of Infancy
Maral Rahvar, M.D; Donald R Chase, M.D
Department of Pathology and Human Anatomy,
Loma Linda University Medical Center, Loma Linda, California
California Tumor Tissue Registry, Loma Linda, California
Fibrous hamartoma of infancy (FHI) is an uncommon benign fibroproliferative tumor of
mesenchymal origin. The entity was first described by Dr. Reye in 1956 as “subdermal
fibromatous tumor of infancy”. The current term, FHI, was proposed in 1965 by Dr.
Enzinger who described 30 cases from the files of the Armed Forces Institute of
Pathology (AFIP). The newer term is currently preferred because of its emphasis on
organoid microscopic appearance, and frequent occurrence in childhood and infancy.
FHI is most common in the first two years of life and often presents as a rapid growing
mass in the subcutis or reticular dermis. Although it is usually freely movable, it may be
fixed to subcutaneous fascia. Boys are affected two to three more times than girls. It
does not spontaneously regress.
The most common location is anterior or posterior shoulder fold, but FHI has also been
reported in the upper arm, thigh, shoulder, back and forearm. It mainly presents as a
solitary lesion but can be multiple.
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Grossly, FHI is poorly circumscribed, firm, grey-white with intermixed irregular small
islands of yellow fat. The proportion of adipose to fibrous tissue varies from case to case.
In lesions where fat occupies a large portion of tumor, the specimen may resemble a
fibrolipoma. The tumor is usually about 4 cm in greatest diameter, but masses as large as
15 cm have been reported.
Histologically, FHI is recognized by the presence of three components forming an
organoid pattern:
(1) intersecting trabeculae of fibrous tissue composed of spindle-shaped cells
separated by collagen bundles,
(2) loosely textured areas consisting of immature round or stellate cells in a
matrix of Alcian blue-positive hyaluronidase sensitive material, and a
(3) varying amount of mature fat.
Although the diagnosis is usually based on H&E examination, immunohistochemical
stains may be helpful. Positive stains may include smooth muscle and muscle-specific
actin reactivity in the trabecular component, and CD34 is occasionally expressed in the
spindle cells.
Local excision is the preferred treatment and recurrences are unusual. Although the
etiology of this tumor is still unknown, some cases have shown cytogenetic abnormalities
including complex (6;12,8)(q25;q24.3;q13), reciprocal translocation of t(2;3)(q31;q21)
and rearrangement of chromosome 1, 2, 5 and 17.
Suggested Reading:
Reye RDK. Considerations of certain subdermal ‘‘fibrous tumors’’ of infancy. J Pathol 1956; 72:
149–154.
Enzinger FM, Fibrous Hamartoma of Infancy. Cancer. 18, 241–8 (1965).
Ritchie EL, Gonzalez-Crussi F, Zaontz MR Fibrous hamartoma of infancy masquerading as a
rhabdomyosarcoma of the spermatic cord. J. Urol. 140(4), 800–1 (1988).
Groisman G, Lichtig C Fibrous hamartoma of infancy: an immunohistochemical and
ultrastructural study. Hum. Pathol. 22(9), 914–8 (1991).
Dickey GE, Sotelo-Avila C. Fibrous hamartoma of infancy: current review. Paediatr Dev Pathol
1999; 2: 236–243.
Fetsch JF, Miettinen M, Laskin WB, Michal M, Enzinger FM. 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. 24(11), 1491–500 (2000).
Imaji R, Goto T, Takahashi Y, Akiyama T, Yamadori I A case of recurrent and synchronous
fibrous hamartoma of infancy. Pediatr. Surg. Int. 21(2), 119–20 (2005).
Yoon TY, Kim JW Fibrous hamartoma of infancy manifesting as multiple nodules with
hypertrichosis. J. Dermatol. 33(6), 427–9 (2006).
Enzinger FM, Weiss SW. Soft Tissue Tumor; 6th edition. Mosby; 2013, 9: 257-283.
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