Discussion
GCT is rare in the clinic and can occur in various parts of the human
body. More than 50% of the reported cases have occurred in the head and
neck, and the tongue is the most frequently involved anatomic site,
followed by skin and subcutaneous tissue, breast, respiratory tract, and
digestive tract. GCT can occur in patients at any age, but is more
common during the fourth to the sixth decades of life and is rare in
children [3]. Very few cases of earlier presentation (younger than
20 years old) have been described [4]. GCTs are twice as common in
women as in men, and its incidence is more common in the
African-American ethnic groups than Caucasians [2]. Familial cases
have rarely been reported [3]. Most GCTs are well-circumscribed
solitary, asymptomatic nodules that grow gradually [5], but multiple
GCTs have also been reported, with an incidence ranging from 3.4% to
20% [1].
GCTs are not easy to detect because they are asymptomatic without
swelling and pain or neurological symptoms, and the diagnosis cannot be
made only by clinical symptoms and therefore, biopsy or fine-needle
aspiration or other pathological examinations may be required [5].
Macroscopic findings showed that the mass is round or oval, generally no
more than 2 cm. The capsule is incomplete without a normal film. The
texture is hard, and the mass is generally gray yellow; its section may
be pale yellow, milky white, or gray white. Under light microscopy,
round cells are observed with rich cytoplasm that may have abundant
eosinophilic granules. The nucleus is small and round, uniform,
centered, and occasionally deviated. The tumor cells are closely
arranged in nests or cords, and occasionally striated muscle fibers are
closely associated with granulosa cells. Under electron microscopy, the
cytoplasm was filled with compound lysosome membrane package with
different sizes and shapes. And more than 30% of the cases of tumor
surface epithelium are pseudoepitheliomatous hyperplasia [6].
Sometimes, the mass is associated with keratosis because its morphology
is extremely similar with the nest of early invasive squamous cell
carcinoma; if neoplastic granular cells beneath the epithelial are not
noticed, it may be easy to misdiagnose a GCT as squamous cell carcinoma
[7]. Immunohistochemical staining showed strong positive expression
of S-100 protein, NSE, and vimentin in tumor cells, and negative
expression of NF and GFAP [8]. However, the diagnosis of GCT is
mainly based on the typical manifestations of tumor cells under light
microscope. Immunohistochemical pathology is often used to distinguish
from other tumors.
Most GCTs are benign in clinical behavior and histomorphology, but
malignant cases have also been reported. The incidence of malignant GCT
is 2%-3%, and such malignant GCTs are most commonly seen in the chest
wall, followed by the thigh [5]. Benign GCTs tend to invade
surrounding tissues and nerves and therefore, local invasiveness is not
the key point in the differentiation between benign and malignant GCTs.
In 1998, Fanburg-Smith et al. proposed for the first time that
histological features of soft tissue GCT could be benign, malignant, and
cell atypia, according to the following six factors: necrosis, spindle
tumor cells, vesicular nuclei with distinct nucleoli, the nucleoplasmic
ratio was greater than 2:1, mitotic figures > 2/10HP, and
cell pleomorphism. GCTs with three or more items are considered as
malignant, those with two items are considered as cell atypia, and the
rest are considered as benign [1,9].
Benign GCTs are usually locally resected along with the surrounding 1 cm
of normal tissue. Tumor recurrence usually occurs within 5 years, and a
few recurrences are due to multicentric growth rather than incomplete
resection of the primary tumor [6]. The prognosis is generally good,
and the malignant transformation rate is low [6]. Malignant GCTs are
prone to local recurrence and metastasis, and the most common metastatic
sites are regional lymph nodes, lung, and bone. Clinically, large tumor
size, rapid growth, and rapid recurrence also suggest the possibility of
malignancy [10]. Some studies have shown that chemotherapy and
radiotherapy cannot significantly improve the clinical course of
malignant GCTs. Extensive local resection and regional lymph node
dissection have been performed when necessary [8]. Close follow-up
should be performed after the operation.
In this case, clinical and imaging diagnosis were difficult, and
diagnosis was confirmed on postoperative pathological results. However,
the lesion in this case had a complete capsule, which was contrary to
the incomplete capsule without normal film reported in previous cases
[7]. In our case, the tumor and the peripheral denatured nerve were
completely removed during the operation, and no signs of recurrence were
observed up to the 3-year follow-up.