Case Report
Suboccipital Solitary Fibrous Tumor Diagnosed by
Fine Needle Aspiration: Report of an Uncommon
Tumor in a Rare Location and a Brief Review of the
Literature
Carolina Fonseca*, Gilmar Costa, Soubhi Alhayek, Abdel-rahman El-Mallah, and Mohamad Aziz
Department of Pathology, American University of the Caribbean, 1 University Drive at Jordan Road Cupecoy, USA
*Corresponding author: Carolina Fonseca, Department of Pathology,
American University of the Caribbean, 1 University Drive at Jordan Road
Cupecoy, 5980 Inkster Road, West Bloomfield, MI, USA, Tel: 530-220-
7996; Email:
fonseca.carolina9@gmail.com
Submitted: 14 June 2019; Accepted: 26 June 2019; Published: 28 June 2019
Cite this article: Fonseca C, Costa G, Alhayek S, El-Mallah AR, Aziz M (2019)
Suboccipital Solitary Fibrous Tumor Diagnosed by Fine Needle Aspiration:
Report of an Uncommon Tumor in a Rare Location and a Brief Review of
the Literature. JSM Clin Cytol Pathol 4: 3.
Solitary fibrous tumors are rare and difficult to diagnose. The occurrence of this entity in the head and neck region constitutes
approximately 6% of the cases and is associated with higher rates of recurrence. We report a case of a 61-year old male diagnosed with
this rare tumor by fine needle aspiration.
Keywords: Solitary fibrous tumor; Head and neck region; Cytology; Fine needle aspiration
SFT: Solitary Fibrous Tumor; FNA: Fine Needle Aspiration
Solitary fibrous tumor (SFT), also known as fibrous tumor
of the pleura, is a rare mesenchymal tumor originating from
the pleura or at virtually any site in the soft tissue. This tumor
was first described by Klemperer and Rabin in 1931 [1]. These
neoplasms are rare, mostly benign and they usually develop
in the pleura. Extrapleural SFTs are rarer and 10 to 15% show
malignant behavior [2]. The diagnosis of SFTs relies on the lesion’s
histological appearance presenting with hemangiopericytic
pattern composed of spindle cells proliferating in a “pattern less
pattern” [3]. The over expression of CD34 and the lack of S-100
expression distinguishes these tumors from other spindle cell
neoplasms [2-4].
Solitary fibrous tumors of the head and neck region constitute
approximately 6% of all SFTs. Due to its rarity, sufficient
data describing this tumor are lacking. According to recent
publications, head and neck SFTs tend to have higher rates of
recurrence than similar tumors in other locations [5]. The risk of recurrence and metastasis seems to be associated with the
size of the lesion, and the histological status of the margins of the
excised tumor [2]. Given the fact that SFTs in the head and neck
are rare and potentially malignant, it is important to increase
physicians’ awareness of this particular tumor, and its inclusion
in the differential diagnosis of soft tissue mass in the head and neck.
A 61-year-old man presented with an enlarged sub
occipital mass which had been present for years but had
recently increased in size. Computed tomography of the neck
demonstrated a heterogeneous appearing soft tissue mass in
the suboccipital region which had increased in size – from 6.8
x 5 x 6.8 cm (6 months prior) to 9.8 x 5.7 x 8.5 cm. Peripheral
areas of intense enhancement and prominent peripheral
vessels were noted. The mass extended cephalad just above
the inion of the occipital bone and caudally to the level of the
C2 spinous process. The mass abutted the adjacent extensor
musculature and extended into the subcutaneous tissues
on the left producing a contour deformity of the overlying
skin. There was mild cortical irregularity and lucency in the
region of the inion not noted previously. Physicians suspected
a soft tissue sarcoma and performed fine needle aspiration
with core needle biopsy of the posterior suboccipital mass.
Diagnostic material was obtained utilizing Fine Needle
Aspiration (FNA). Cytology study revealed sheets, clusters,
and single cells with bland cytomorphologic features and
prominent plasmacytoid morphology predominantly
in perivascular arrangements. Rare mitoses and no necrosis were
noted (Figure 1A,B,C). An extended immunocytochemistry panel
was performed for tumor characterization. The only two antibodies
with positive and strong staining were CD34 and CD99 (Figure 1D)
with focal weak positive chromogranin staining negative stains
included: S100, HMB45, Melan-A, EMA, AE1/AE3, CAM5.2,
HMW-CK903, P40, CD31, GFAP, CD163, Desmin, SMA,
and Synaptophysin. The tumor proliferation was low with
less than 2% nuclear staining with Ki-67. A diagnosis of low grade mesenchymal neoplasm, more specifically solitary fibrous
Tumor was made.
-
Figure 1: Fine needle aspiration of the subocciptal mass, cytology smears. View Figure
A & B: Sheets, clusters, and single spindle cells with bland cytomorphologic features composed of spindle cells proliferating in a “pattern less
pattern” H&E stain; X 40
C: Prominent plasmacytoid morphology with mild atypical features showing irregular nuclear membrane, prominent nucleoli and no necrosis H&E
stain; X 100
D: Immunocytochemistry CD99 positive for the tumor cells
The tumor was fully excised (10.2 x 8 cm) with wide safe
margins. The patient did not require post-operative radiation or
chemotherapy, and he was free of recurrence and metastasis at
his 4 year follows up. Patient lost to follow up after that.
We are presenting this case to contribute to the growing
literature describing SFT and to emphasize that the diagnosis
of SFT can be made on cytology samples alone including
immunohistochemistry studies on cytologic preparation. The
case being presented here was diagnosed with cytology sampling
and immunohistochemistry alone. As emphasized by a recent
publication in the Journal of Cytology, correctly diagnosing
tumors like this preoperatively prompts an aggressive resection
and decreases the chances of recurrence [6].
The differential diagnosis of SFTs is broad and includes
benign and malignant tumors [7]. The diagnosis can be difficult
as the morphological features of this tumor overlap with a
range of other myxoid spindle cell neoplasms such as dendritic
fibromyxolipoma, lipomatoushemangiopericytoma, cellular
angiofibroma and spindle cell lipoma [8]. The key features of SFT
include abundant pale myxoid stroma, staghorn blood vessels
and pattern less arrangement of spindle cells that are separated
by collagen fibers [9-11].
Only a few cases of solitary fibrous tumors in the occiptocervical
region have been reported in the English literature, for this
reason, physicians might not include this rare tumor in their
list of differential diagnoses when presented with a mass in this
region. However, extrapleural SFTs have been shown to present
malignant behavior – including recurrence and metastasis [2] and
should be considered in the differential diagnosis of extrapleural
masses, particularly in the occiptocervical region [9]. The case
presented here contributes to the recognition of this uncommon
tumor in a rare location.
Most recent molecular studies performed on SFT
demonstrated numerous karyotypic aberrations in extrapleural
SFTs. The most common included chromosome gain, loss and
partial deletion. An intrachromosomal rearrangement has also
been described. Although the etiology of the neoplasm remains
largely unknown, the pathogenesis seems to be related to an
NAB2–STAT6 fusion gene due to paracentric inversion on
chromosome 12q13 [12].
In 2014, a group of physicians reported a SFT that recurred
ten years after the initial removal surgery and invaded the atlas
[2]. This case exemplifies the potential malignant behavior of this
particular tumor. The recurrence of SFTs in the head and neck
region has been related to the incomplete excision of lesions
[4,7]. This location is frequently regarded as challenging for
surgeons, and it is not always feasible to attain clear surgical
margins. When wide excision is not possible, marginal resection
and radiotherapy may be an alternative treatment option if the patient is in low risk group according to the risk stratification
model. And when wide excision is not possible close follow-ups
including annual MRIs are recommended for at least 10 years
[4,6,13]. Radiotherapy treatment has been suggested for patients
with unresectable and/or recurrent tumors, but there is no data
reporting the long term efficacy of this treatment approach [14,4].
It is our hope that this report raises awareness of what
remains an unmet need in the diagnosis and management of
solitary fibrous tumors and that continued investigation drives
further development of efficacious diagnosis and safe treatments
for improving patient outcomes.