.

1. Give an overview of the
other histopathological
variants of SCC

2. Variants of
squamous cell
carcinoma
There are important variants of squamous cell
carcinoma which may present particular diagnostic
difficulties;
these include:
1. Verrucous carcinoma
2. Spindle cell carcinoma
3. Adenoid squamous cell carcinoma
4. Pseudovascular adenoid squamous cell carcinoma
5. Adenosquamous carcinoma
6. Basaloid squamous cell carcinoma.

3. Verrucous
carcinoma.
indolent lesion characterized by an endophytic
papillary or verruciform surface, a pushing
invasive front and a high degree of differentiation
with little cytological atypia.

4. The photomicrograph shows the invagination of
epithelium, the invasive downward growth of
the epithelium, and the chronic inflammatory
cells just below the invading epithelium. The
lesion displays a highly keratinized surface that
is papillary, with inflammatory cell infiltrate
immediately adjacent to the margins of the
invading neoplasm.
Verrucous carcinoma-broad bulbous pushing rete
ridges with parakeratotic plugging (H&E stain, ×100)

5. Spindle ceil
carcinoma
The oral cavity spindle cell carcinomas are usually
fungating ulcerative lesions which arise most
commonly on the lips, the spindle cell component
probably represents anaplastic change in an
otherwise conventional squamous cell carcinoma.
tongue or gingivae and have a poor prognosis.

6. A) Oral spindle cell carcinoma. Clinical
aspect showing an ulcerated exophytic
mass on the upper alveolar ridge.
B) (B) Proliferation of dysplastic spindle
cells (H&E, original magnification – OM
100×).
C) (C) Transition between tumoral
spindle cell and dysplastic squamous
cell components (H&E, OM 400×).
D) (D) Presence of abundant mitosis
(H&E, OM 400×; arrows)

7. Elongated and serpentine spindle cells infiltrate widely into the connective tissues
and usually show obvious features of Mlignancy including bizarre pleomorphic
nuclei and many abnormal mitoses
the diagnosis must be made by the demonstration of an origin from overlying
epithelium or by the finding of conventional squamous cell carcinoma elsewhere.

8. Adenosquamous carcinoma.
This carcinoma is a distinct entity which may arise at any site in the upper aerodigestive
tract as well as the GI tract and skin.
It is relatively rare in the oral cavity but when it does arise it is an aggressive neoplasm
with a worse prognosis than squamous cell carcinoma.
The lesion is characterized by the presence of areas of squamous cell carcinoma closely
associated with, but separated from, areas of adenocarcinoma with glandular
differentiation and mucin production.
The lesion arises from surface epithelium but simultaneously involves the ducts of minor
salivary glands.

9. (a) Stratified squamous epithelium (indicated by arrow mark) infiltrating into
underlying connective tissue stroma (indicated by an asterisk) (H&E stain, ×40). (b)
Squamous component (indicated by arrow mark) and glandular component (indicated
by asterisk) (H&E stain, ×100)

10. Adenoid
squamous cell
carcinoma
may resemble adenosquamous carcinoma, but in
this case the glandular pattern is due to loss of
adhesion and acantholysis of
cells in the centre of islands of conventional
squamous cell carcinoma.
Accordingly this lesion is also referred to as
'pseudoglandular' or 'acantholytic carcinoma’.
Mucin is not produced.

11. Adenoid squamous cell carcinoma -pseudoglandular pattern with acantholytic tumor cells.

12. Pseudovascular
adenoid
squamous cell
carcinoma
(PASCC)
is an uncommon histological variant of squamous
cell carcinoma that can mimic vascular
neoplasms, particularly angiosarcoma, in its
morphologic characteristics.

13. (a, b) Tumor with anastomosing vessel-like channels, lined by a single layer of malignant cells
(c, d) showing tumor with dilated and congested blood vessels (H and E, ×100)

14. Basaloid
squamous cell
carcinoma
variant of squamous cell carcinoma which arises
most often in the tongue and is again associated
with a worse prognosis and a higher incidence of
distant metastases
The diagnosis is made on the basis of a
conventional squamous cell carcinoma arising
from surface epithelium with areas showing solid
lobules or islands of small darkly staining and
pleomorphic basaloid cells.
The basaloid component usually predominates
and shows an infiltrative pattern with frequent
central comedo necrosis.

15. Basaloid squamous cell carcinoma biphasic tumor
showing basaloid malignant islands with
peripheral palisading and comedonecrosis (arrow)
(H&E stain, ×100). Inset depicts squamous
differentiation with keratin pearl formation
(arrowhead) (H&E stain, ×100)