Primary Cutaneous Myxoid Spindle Cell Squamous Cell Carcinoma of the Scalp: A Case Report
Recep BEDİR, Mehpare SUNTUR, Orhan SEMERCİ
Department of Pathology, Recep Tayyip Erdoğan University, School of Medicine, RIZE, TURKEY
Keywords: Squamous cell carcinomas, Cutaneous, Myxoid spindle cell variant
Cutaneous squamous cell carcinomas are the second most frequent type of non-melanoma skin cancer. A 78-year-old man with a slow-growing
but large nodular lesion on his scalp presented to the hospital. The nodular lesion was excised. Histologically, the lesion was diagnosed as a
primary cutaneous myxoid spindle cell squamous cell carcinoma, which is the subject of this case report. Extracellular mucin production is an
even less common finding in SCC. We also aim to discuss the histological and immunohistochemical findings for distinguishing MSC SCC from
other primary cutaneous and metastatic spindle cell neoplasms with myxoid stroma.
Primary cutaneous myxoid spindle cell squamous cell
carcinoma (MSC SCC) was first identified by Yang et al.
. This rare variant of SCC has been reported in only
7 cases in the literature to date 2
. Here, we present an
MSC SCC case located on the scalp of a 78-year-old male
patient by employing immunohistochemical analysis for
the differential diagnosis.
A 78-year-old male presented to the clinic with an ulcerated
nodular lesion at the parietal region of the scalp that had
failed to heal and had become gradually larger in the last
2 years. The lesion was removed by wide surgical excision.
An ulcerated nodular lesion with a diameter of 0.5 cm was
macroscopically observed on the cross-sectional surface of
the 0.6 cm-thick tissue covered with skin 1 cm in diameter.
Microscopic examination revealed a tumor with infiltration
of single cells/multiple groups of cells and cell groups
in prominent myxomatous stroma of the dermis and
ulceration in the epidermis. The tumor comprised atypical
epithelial cells with a spindle-like plasmacytoid appearance
and large hyperchromatic nuclei with prominent nucleoli.
The storiform pattern of the tumor mimicked myxoid
sarcoma (Figure 1A-D
). There was mild pleomorphism
in the neoplastic cells, increased mitotic activity, and
peri-neural invasion, but no necrosis or lymphovascular
invasion. No tumor was observed within the surgical limits.
The invasion depth of the tumor was 0.3 cm with a diameter of 0.7 cm (stage T1). Immunohistochemical examination
for the differential diagnosis of malignant melanoma and
mesenchymal tumors revealed negative staining in the
neoplastic cells for S-100, HMB-45, MART1, SMA, and
desmin. The neoplastic cells showed diffuse staining with
Pan-cytokeratin (AE1/3), P40, and vimentin (Figure 2AD
The Ki-67 proliferation index of the tumor was high
(40-50%) (Figure 2A-D
). Alcian blue staining was positive
in the myxoid stroma (Figure 3
). No intracellular mucin
accumulation was observed with the Periodic Acid-Schiff
stain in combination with diastase (PAS-D). Based on these
results, the case was diagnosed as MSC SCC. No enlarged
pathological lymph node was observed on ultrasonography
(USG) examination of the head and neck region. No
additional treatment was needed for the patient and followup
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|Figure 1: A) Tumor showing infiltration as single cells and cell groups in prominent myxomatous stroma of the dermis and ulceration in
the epidermis (H&E; x200). B) The tumor consists of atypical epithelial cells with spindle-like morphology and plasmacytoid appearance
(H&E; x400). C) Tumor showing spindle cell proliferation with prominent myxoid stroma (H&E; x400). D) Tumor showing storiform
pattern mimicking a myxoid sarcoma (H&E; x400).
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|Figure 2: A) The tumor showed diffuse positivity for p40 (IHC; x200). B) The tumor showed diffuse positivity for AE1/3 (IHC; x200).
C) The tumor showed a high Ki-67 proliferation index (IHC; x200). D) The tumor was diffuse positive for vimentin (IHC; x400).
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|Figure 3: Alcian blue staining was positive in the myxoid stroma (Alcian blue; x200).
Written informed consent was obtained from the patient
who was presented in this case report.
Intracellular mucin production in cutaneous MSC SCC is
rarely seen and this condition is named adenosquamous
carcinoma that is a more aggressive variant of SCC.
Stromal mucin in SCC is rare 1-6
. Primary cutaneous
SCC is the second most frequently encountered skin cancer
and has many subtypes. Cutaneous spindle cell SCC is a
rarely seen variant and has lower risk of metastasis. This
risk increases in relation to previous skin damage and
immune suppression 3
. The sarcomatoid carcinomas on the mucosal surface have a worse prognosis than those with
cutaneous localization 7
Yang et al. 1 have identified the histological criteria of
the diagnosis of MSC SCC by using 6 cases. The inclusion
criteria of MSC SCC include significant myxoid stromal
changes occurring in more than half of the lesion, positive
staining for neoplastic spindle (and squamous) cells with
a minimum of one cytokeratin (CK) and especially high
molecular weight CK (HMWCK), and negative staining for
melanocytic and mesenchymal markers of neoplastic cells
(S-100, MART-1, actin, myogenin, and desmin). The first
3 criteria were met in all 6 cases. Similar to the histological
criteria identified by Yang et al., our case showed negative
staining with mesencyhmal and melanocytic markers and
positive staining with epithelial markers, and there was mucin production in more than half of the lesion. Since
MSS SCC is a rarely seen type of carcinoma, it is very
difficult to determine the prognosis. Local recurrence was
identified in a limited number of cases by Yang et al. and
metastasis was observed in one case. They reported that
the invasion depth of the tumor was the most important
indicator of an aggressive course 1.
The differential diagnosis of MSS SCC includes myxoid
sarcomas (such as myxofibrosarcoma and malignant
peripheral nerve sheath tumor), spindle cell atypical
fibroxanthoma (AFX) and spindle cell melanoma. The
negativity of melanocytic and mesenchymal markers
excludes these tumors. However, only vimentin among the
mesenchymal markers shows positive staining in spindle
cell SCC 1-3.
MSC SCC differs from other cutaneous and mucocutaneous
SCCs. MSC SCC lacks mucin-containing glandular
structures in contrast to adenosquamous SCC. Adenosquamous
carcinoma SCC is characterized by the presence
of squamous cells, mucin-producing cells and, in some
cases, glandular structures 3,7,8. The intracellular mucin
in adenosquamous carcinoma is epithelial mucin (sialomucin)
and stains with mucicarmine, and the glandular
structures express CEA when present 3. MSC SCC is
characterized by a mucinous (myxoid) stroma that is positive
with Alcian blue but true epithelial type mucin is not
observed (mucicarmine should be negative). In addition,
signet ring-like cells were a minor component but no intracytoplasmic
mucin was detected within these tumor cells.
Thus, unlike cutaneous SCC with mucinous metaplasia
(also referred to as signet ring cell SCC), MSC SCC lacks signet ring cells with intracytoplasmic mucin 8.
The chronic long-term exposure to ultraviolet (UV)
radiation has been reported to be responsible for the
pathogenesis of most SCCs 5. It has been reported that
long-term UV exposure likely plays the key instigator role
in the epithelial-mesencyhmal transition pathways causing
the phenotypic changes observed in spindle cell SCC. HPV
plays a major role in SCCs localized in the genital region.
Although HPV DNA can be found in 45% of all penile
and vulvar SCCs, the highest incidence of HPV DNA is
seen in basaloid-type penile SCC cases 9. In our case, the
condition was localized to the scalp and there was exposure
to UV radiation.
In conclusion, we describe an unusual variant of spindle
cell SCC with prominent myxoid features that may mimic
myxoid AFX, myxoid sarcomas and, less frequently,
melanoma with myxoid change. The differential diagnosis
of spindle cell SCCs with myxoid stroma should be made
by using melanocytic and mesenchymal markers in order
to distinguish them from all the other potential tumors,
and the diagnosis should be confirmed by using epithelial
markers. Moreover, the patients should be followed up for
a long time in terms of recurrence and metastasis.
CONFLICT of INTEREST
There are no conflicts of interest.
Concept: RB, Design: RB, Supervision: RB, MS, OS,
Resources: RB, MS, OS, Materials Data Collection and/or
Processing: RB, MS, OS, Analysis and/or Interpretation:
RB, OS, Literature Search: RB, Writing Manuscript: RB,
Critical Review: RB.
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