Baylor University Medical Center Proceedings July 2017 - 320

Figure 2. (a) Hematoxylin and eosin stain of the fine needle aspiration cell block. (b) S100 stain of the core biopsy. (c) CD68 stain of the core biopsy.

abundant eosinophilic cytoplasm. Immunohistochemical
stains performed on the core biopsy showed that the tumor
cells were negative for pan keratin, smooth muscle actin,
HMB-45, and MART-1. The tumor cells were positive for
S100, CD68, vimentin, inhibin, and SOX 10, with a low
proliferative rate (<5%) on Ki 67. These results were consistent with a granular cell tumor.
The patient underwent magnetic resonance imaging of the
brain, which did not show any metastatic deposits. Further
histologic evaluation of the lesion on the left aspect of T4 was
negative for malignancy (scant ﬁbrous tissue and bone). However, this sample was not felt to be adequate, and since the
lesion had increased SUV activity the multidisciplinary team
suggested a surgical corpectomy and vertebroplasty of the T4
lesion. A myeloma panel was negative.
Our patient had severe emphysematous changes on his CT
scan and continued to smoke, which were most likely contributing to his chronic cough.
DISCUSSION
Granular cell tumors were originally called granular cell
myoblastomas, as they were thought to be of myogenic origin. However, recent ultrastructural, immunohistochemical,
and histologic studies revealed that they are more likely to
be of Schwann cell origin (1-3). Th ey can be benign or
malignant. Granular cell tumors are rare, and the literature
describing them is in the form of case reports and series.
Our search of the literature did not reveal any prior report
describing a pleural-based occurrence of a granular cell tumor. Malignant granular cell tumors are even rarer (3), accounting for about 1% to 2% of all granular cell tumors,
although there remains some controversy regarding the true
incidence, as there is disagreement regarding the histologic
classiﬁcation (4).
A study that attempted to describe the morphologic spectrum and immunohistochemical analysis of 12 granular cell
tumors (10 benign and 2 malignant) demonstrated S100 reactivity in 9 patients who had it performed, CD68 positivity in 10
cases who had it performed, vimentin in 5 cases, and inhibin in
3 of the 6 cases performed. The two cases that were not positive
for S100 involved old paraﬃn blocks. Immunohistochemically,
most granular cell tumors express S100, neuron-speciﬁc enolase, and CD68. Calretinin positivity and protein gene product
320

9.5 and inhibin expression have been documented as possible
additional markers that could be used for substantiating the
diagnosis of granular cell tumors. Calretinin expression has been
attributed to a neural cell lineage, while the reasons for inhibin
positivity are not clear (2).
In a series of 73 cases of granular cell tumor, FanburgSmith et al deﬁned malignancy as the presence of three or
more of six criteria that included necrosis, spindling of tumor cells, presence of vesicular nuclei with large nucleoli,
increased mitotic rate (>2 mitoses/10 high-power ﬁelds at
200× magnification), a high nuclear-to-cytoplasmic ratio, and
pleomorphism (4).
In the chest and respiratory tract, Kutuya and Akiduki
described an asymptomatic young woman who had an illcircumscribed mass with peripheral inﬁltration in the medial
right upper lung ﬁeld on chest radiograph (5). CT showed
an intrabronchial mass that was found to be benign with the
granules positive for S100. A right upper lobectomy and lymphadenectomy were done.
In a 10-year review of tracheobronchial granular cell tumors in the Dutch Network and National Database for Pathology, 31 tumors were registered in 30 patients. About half
of the patients were asymptomatic. All the tumors described
were benign. Eighteen of the 30 patients received no speciﬁc
treatment. The other patients received either surgery, electrocautery, or Nd-YAG laser treatment. The surgical treatments
oﬀered were tracheal resection and subsequent reconstruction
(for tracheal tumors) and pneumonectomy or lobectomy for
bronchial tumors. The patients who had surgery had remission
for up to 10 years, and those with residual disease remained
stable (6). Multiple reports have described tumors at myriad
other locations (7-10).
1.
2.

Abrikossoﬀ A. Uber Myome, ausgehend von der quergestreiften Willkürlichen muskulatur. Virchows Arch Pathol Anat 1926;260(1):215-233.
Rekhi B, Jambhekar NA. Morphologic spectrum, immunohistochemical analysis and clinical features of a series of granular cell tumors of soft
tissues: a study from a tertiary referral cancer center. Ann Diagn Pathol
2010;14(3):162-167.
Nath D, Gupta A, Arava S, Jain D, Madan K. Synchronous existence
of granular cell tumor and small cell carcinoma of the lung: an unusual
entity. Indian J Pathol Microbiol 2016;59(1):90-92.
Fanburg-Smith JC, Meis-Kindblom JM, Fante R, Kindblom LG. Malignant granular cell tumor of soft tissue: diagnostic criteria and clinicopathologic correlation. Am J Surg Pathol 1998;22(7):779-794.

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