Los Angeles Society of Pathology
Case Presentations
June 14, 2005
California Tumor Tissue Registry’s
Case of the Month
www.cttr.org, vol 7(12), Sept, 2005
“A 38-year-old woman with a fixed left inguinal mass”
A 38-year-old Chinese woman presented with a left groin mass that had been gradually
increasing in size over three months. A review of systems revealed no fever, abdominal
pain, cough or other complaints. On physical exam there was a poorly defined, fixed
mass in the left inguinal region that measured 8.0 x 6.0 x 5.0 cm. No other abnormalities
were found on physical exam. The chest film was unremarkable. The hemoglobin was
11.3, the red blood cell count 3.84, and white count 8 composed of 63% neutrophils and
30% lymphocytes. The patient underwent surgery for resection of the mass.
A 7.0 x 6.0 x 5.0 cm round to ovoid tan mass was submitted for pathologic evaluation.
On cross-section, the center of the mass was firm and gray-white with a peripheral rim of
compressed, hemorrhagic lymphoid tissue (Fig. 1 - similar case).
Upon histologic examination, the nodal architecture was replaced by neoplastic spindle
cells arranged in short interlacing fascicles that tended to palisade about dense, ovoid to
stellate-shaped eosinophilic fibers (Figs. 2,3). There were also multiple hemosiderin-
laden macrophages in the background indicating past hemorrhage (Fig. 4). The spindle
cells were reactive for vimentin and smooth muscle actin, particularly in the eosinophilic
fibers, and were negative for desmin.
DIAGNOSIS
Palisaded myofibroblastoma (aka “intranodal hemorrhagic spindle-cell tumor with
amianthoid fibers”)
Rojas L. Heather, MD, Jun Wang, MD, and Donald R. Chase, MD
Loma Linda University Medical Center, California, U.S.A.
Palisaded myofibroblastoma, also known as intranodal hemorrhagic spindle-cell tumor
with amianthoid fibers, is an uncommon entity. Because of its rarity we do not know its
incidence. The neoplasm has a predilection for the inguinal lymph nodes, and before the
advent of routine use of immunohistochemistry, many were diagnosed as intranodal
neurilemoma or leiomyoma.
In 1989, this benign neoplasm was simultaneously described by Weiss et al, and Suster
and Rosai. Weiss named the neoplasm palisaded myofibroblastoma, while Suster and
CTTR’s Case of the Month September, 2005 1
Rosai coined the descriptive term, “intranodal hemorrhagic spindle-cell tumor with
amianthoid fibers.” For brevity sake, the former designation is preferred. The tumor
preferentially involves the inguinal lymph nodes, but also has been reported in the
submandibular gland and mediastinum.3
Patients typically present with recent growth of a solitary groin mass or swelling that may
be slightly tender upon palpation. No enlargement of other lymph node groups or
manifestations of systemic diseases are found. On gross examination, the lesions are
typically well-circumscribed, round to oval masses with an average dimension of 3-4 cm.
Upon cross-sectioning, the tumors are tan and rubbery with occasional flecks of
hemorrhage surrounded by a thin rim of compressed hemorrhagic lymphoid tissue.
On low power, a rim of compressed lymphoid tissue surrounds a band-like pseudocapsule
which encases the tumor. The tumor is predominately comprised of numerous fascicles
of spindle cells that have fibrillary, eosinophilic, cytoplasm and elongated nuclei with
dispersed chromatin. The spindle cells tend to aggregate about irregular round to stellate,
dense, eosinophilic mats of collagen deposition that have been classified as amianthoid
fibers (see below). The deeply eosinophilic collagen core of the fibers is usually
surrounded by hair-like eosinophilic spokes. Some aminathoid fibers may have small
vessels at their center. The fibers may also coalesce with the thickened pseudocapsule.
Scattered throughout the tumor are vessels, red blood cells, many hemosiderin-laden
macrophages, and occasional inflammatory cells. Mitoses tend to be rare to infrequent
with a maximum count of one to two per 10 high-power fields.
Amianthoid fibers are composed of abnormal collagen fibrils that form thick collagen
bundles that range from 200-1000 nm. They are typically found in connective tissue
disorders such as pseudoxanthoma elasticum, Ehlers Danlos, Marfan’s syndrome, and
cartilage involved with osteoarthritis. Uncommonly, these fibers are found in tumors of
mesenchymal or soft tissue origin. In 1992, Skalova et al reported that the foci of
collagen widely referred to as amianthoid fibers within palisaded myofibroblastoma
actually contained fibrils predominately of conventional diameter (25-100 nm) therefore
excluding them from qualifying as true amianthoid fibers5.
The source of these tumors appears to be smooth muscle and/or myofibroblasts. By
electron microscopy, they have intracytoplasmic microfilaments with focal densities and
profiles of well-developed rough endoplasmic reticulum6. The major component is actin
which condenses in the cytoplasm and is extruded from the spindle cells to form the
fibers.
Immunohistochemistry shows the spindled tumor cells to be strongly positive for muscle
actin, myosin, and vimentin, particularly at the periphery of the amianthoid fibers. The
cells fail to stain for desmin, factor VIII-related antigen, Ulex europaeus lectin,
glial fibrillary acidic protein, Leu-7, synaptophysin, epithelial membrane antigen and
keratin. Recent reports show that the spindle cells may be positive for cyclin D14. The
amianthoid fibers are reactive for type I and III collagen.
CTTR’s Case of the Month September, 2005 2
Palisaded myofibroblastomas may mimic intranodal neurilemoma because the
amianthoid fibers surrounding wavy spindle cells in a palisaded pattern mimics the
Verocay bodies found in a neurilemoma/schwannoma. However true Antoni A and
Antoni B areas are not found, and immunostaining is negative for S-100 protein.
The main differential diagnosis is lymphadenopathic Kaposi’s sarcoma (KS). The tumor
can occur in the context of endemic (African) KS, immunosuppression, acquired
immunodeficiency syndrome, multicentric Castleman’s disease, leukemia or lymphoma.
However, primary KS of the lymph node is exceedingly rare in otherwise healthy
individuals with no immunocompromise.7-9 Both palisaded myofibroblastoma and
Kaposi’s sarcoma have fascicles of spindled cells with scattered vascular spaces and foci
of hemorrhage. However, Kaposi’s typically has more mitoses, nuclear atypia,
extravasated blood cells, and intracytoplasmic round hyaline bodies that are PAS positive
and diastase resistant.
Palisaded myofibroblastoma behaves in a benign fashion and tends to be surgically
“cured.” There have been two reported cases of recurrent tumor and no reports of
metastasis10. This benign neoplasm is important to be knowledgeable of because of its
characteristic presentation and histologic appearance and the ramifications of
misdiagnosing it as a poor actor such as sarcoma.
1. Weiss SW, Gnepp DR, Bratthauer GL. Palisaded myofibroblastoma. A benign mesenchymal tumor of
lymph node. Am J Surg Pathol. 1989 May;13(5):341-6.
2. Suster S, Rosai J. Intranodal hemorrhagic spindle-cell tumor with "amianthoid" fibers. Report of six
cases of a distinctive mesenchymal neoplasm of the inguinal region that simulates Kaposi's sarcoma. Am J
Surg Pathol. 1989 May;13(5):347-57.
3. Alguacil-Garcia, A Intranodal myofibroblastoma in a submandibular lymph node. A case report. Am J
Clin Pathol 1992 Jan ; 97(1): 69-72.
4. Kleist B, Poetsch M, Schmoll J. Intranodal palisaded myofibroblastoma with overexpression of cyclin
D1. Arch Pathol Lab Med. 2003 Aug;127(8):1040-3.
5. Skalova A, Michal M, Chlumska A, Leivo I. Collagen composition and ultrastructure of the so-called
amianthoid fibres in palisaded myofibroblastoma. Ultrastructural and immunohistochemical study. J
Pathol. 1992 167: 335-340.
6. Hisaoka M, Hashiomoto H. Daimaru Y. Intranodal palisaded myofibroblastoma with so-called
amianthoid fibers: a report of two cases with a review of the literature. Pathol Int. 1998 Apr;48(4):307-
12.
7. Berman MA, Nalesnik MA, Kapadia SB, Rinaldo CR, Jr, Jensen F. Primary lymphadenopathic Kaposi’s
sarcoma in an immunocompetent 25-year-old man. Am J Clin Pathol 1986;86:366–369.
8. Benzanini M, Togni R, Barabareschi M, Parenti A, Palma PD. Primary Kaposi’s sarcoma of intraparotid
lymph node. Histopathology 1992;21:489–491.
9. Josephson J, Goldofsky E, Wening B. Primary Kaposi’s sarcoma of an intraparotid lymph node in a non-
immunocompromised patient. Otorinolaryngol Head Neck Surg 1988;99:341–343.
10. Creager AJ, Garwacki CP. Recurrent intranodal palisaded myofibroblastoma with metaplastic bone
formation. Arch Pathol Lab Med. 1999 May;123(5):433-6.
CTTR’s Case of the Month September, 2005 3