18
cytology of Soft Tissue, Bone, and Skin
Rare single-case reports in the literature document the iden-
tification by cytologic methods of infections such as cutaneous
cryptococcus, leishmaniasis, and leprosy, but these are unusual
in common practice.193-195
Other conditions occasionally seen include rheumatoid
nodules and sarcoidosis. Rheumatoid nodules are composed of
granulomas with necrosis, showing epithelioid histiocytes, giant
cells, and debris in a bloody background.
Cutaneous sarcoidosis is uncommon and is not usually aspi-
rated as the enlarged lymph nodes that can be present in this
disease may be the first site to be biopsied. The cytologic pic-
ture is granulomas, usually non-necrotizing, with giant cells and
scattered inflammatory cells.
Calcinosis cutis diagnosed by FNAB has been reported and
consists of amorphous granular material of calcium mixed with
histiocytes.196
1
Fig. 18.47 Herpes. Fluid from base of skin vesicle showing pathognomonic
features of herpes simplex virus. Note the multinucleated enlarged cells
with viral inclusions in contrast to the normal squamous cells of the skin
(Papanicolaou x HP).
Neoplastic
Basal cell carcinoma
Basal cell carcinoma is the most common skin cancer. It occurs
mostly in sun-damaged skin in elderly patients. The tumor is slow
growing and can present as a nodule or ulcer. It can be sampled
by both curetting or FNAB. Histologically, it is characterized by a
proliferation of small basaloid keratinocytes with an outer layer
of palisading cells (Fig. 18.48A). The cytology specimens from
basal cell carcinoma show small and large clusters with periph-
eral palisading and a lobulated configuration. The tumor cells
are mostly uniform in size and shape (Fig. 18.48B). They have
a high N/C ratio and very little cytoplasm. The nuclei are round
to oval with a smooth border, hyperchromatic with fine granular
chromatin pattern, and one or two small distinct nucleoli. The
single cells show similar cytological features. Occasionally, the
nuclei are flattened, indented, or angulated with coarser chro-
matin pattern. Additional features seen in some cases include
the presence of mucinous material, squamous and sometimes
keratinized tumor cells, and pigment-containing cells. The muci-
nous material is metachromatic in Giemsa-stained slides.197 The
differential diagnosis includes squamous cell carcinoma, Merkel
cell carcinoma, and skin appendage tumors.
Key features of basal cell carcinoma
• Small and large clusters with peripheral palisading and
lobulated configuration;
• Round hyperchromatic nuclei with high N/C ratio,
fine granular chromatin pattern, and one or two small
distinct nucleoli;
• Additional features: mucinous material, squamous
and sometimes keratinized tumor cells, and
pigment-containing cells
Squamous cell carcinoma
Squamous cell carcinoma of skin also usually arises from sun-
damaged areas, but it can also arise
de novo.
It usually presents
as a shallow indurated ulcer or it can form a large fungating
0
Fig. 18.48 Basal cell carcinoma. (A) Histologic section. Proliferation of small keratinocytes with outer layer of palisading cells (H&E x MP). B) Smear. Clusters of
atypical cells with peripheral palisading and lobulated configuration (Papanicolaou x MP).
503
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