Dermatofibroma with Verocay Body-Type Palisading Features and a Brief Discussion on Potential Schwannoma Mimickers of the Skin
Yunus Baran KOK, Cuyan DEMIRKESEN
Acibadem University, School of Medicine, Department of Pathology, ISTANBUL, TURKEY
Keywords: Dermatofibroma, Palisading, Verocay
Several types of cutaneous tumors can show palisading features or the so-called rippled pattern. The list includes adnexal tumors such as
trichoblastoma and sebaceoma, basal cell carcinoma, leiomyoma, perineuroma, myofibroblastoma, and even malignant melanoma.
Dermatofibroma, which is known for having a large variety of histological patterns, is also in the list. Here we present a case of dermatofibroma
with palisading features strikingly similar to Verocay bodies of schwannoma.
Dermatofibroma (cutaneous fibrous histiocytoma) is a
common skin tumor well known by pathologists, although
the wide varieties of its histological appearance can make
it a mimicker of other, benign or malignant, skin tumors.
Histopathological classification of dermatofibroma can be
made by its architectural (deep penetrating, aneurysmal
etc.) or cellular (clear cell, monster cell etc.) peculiarities, or
both 1. One histological pattern can be prominent or two
or more histological patterns can be combined in the same
tumor (composite dermatofibromas). A palisading type is
rarely seen (2 in 200 dermatofibromas in one study), and
it includes other tumors in the differential diagnosis, also
rarely presented on the skin, such as schwannoma 2. Here,
we aim to present a case of this rare dermatofibroma variant
and discuss cutaneous tumors with nuclear palisading
features resembling Verocay bodies.
The patient was a 48-year-old male with no remarkable
medical history. The dermatologist described widespread
papular lesions on the chest and sent a punch biopsy with
two clinical prediagnoses as eruptive dermatofibroma and
histiocytosis. Microscopic sections revealed a neoplasm
infiltrating the dermis and overlying a hyperkeratotic and
hyperplastic epidermis (Figure 1A). The neoplasm consisted
of a diffuse proliferation of spindle and ovoid cells. The
most superficial portion of the tumor was relatively cellular
with a few multinucleated giant cells (Figure 1B). The deep
portion of the tumor showed a storiform pattern with short
fascicles, collagenous stroma, fibrohistiocytic proliferation,
and small clusters of foamy macrophages, giving this
part of the tumor a more conventional dermatofibroma
appearance (Figure 2A). In between, there was a zone of
palisading cells, indistinguishable from the Verocay bodies
of schwannoma (Figure 2B). The nuclei of these tumor cells were aligned in rows or palisades, and the cell processes were
fused into eosinophilic masses, forming Verocay bodies.
A brief immunohistochemical panel, consisting of anti-
CD34, anti-Factor XIIIa, and anti-S-100, was performed to
make the differential diagnosis between dermatofibroma
and schwannoma, and to rule out dermatofibrosarcoma
protuberans. In all compartments including Verocay
body-like areas, the tumor cells showed immunoreactivity
for Factor XIIIa while they were negative for CD34 and
S-100 antibodies, and the latter two excluded DFSP and
schwannoma, respectively (Figure 2C). Therefore, the
diagnosis was palisading dermatofibroma.
Click Here to Zoom
|Figure 1: A) Neoplasm infiltrating dermis in a diffuse manner.
At low magnification, a blend of different patterns can be seen.
(H&E; x10). B) Upper part of the tumor. This part is cellular,
composed of spindle and ovoid cells. Overlying epidermis shows
hyperkeratotic and hyperplastic changes. (H&E; x40)
Click Here to Zoom
|Figure 2: A) Middle part of the tumor with a striking Verocaybody
like appearance. Acellular hyaline zones are lined with
palisading elongated cells. This is a typical feature of schwannoma.
(H&E; x100). B) Deeper part of the tumor. Fascicles of spindle
cells, scattered inflammatory cells, and foamy macrophages are
seen. These findings are typical for fibrohistiocytic tumors. (H&E;
x100). C) Cytoplasmic Factor XIIIa expression of the tumor. Both
Verocay body-like (left half of the figure) and fibrohistiocytic
(right half of the figure) parts of the tumor are positive for the
antibody. (IHC; x100).
Verocay body is described by rows of elongated palisading
nuclei with alternating acellular zones. Laminin
overexpression 2 and increased phospholipid deposition
in the cellular matrix 3 are considered in the pathogenesis.
Although it is thought to show neural differentiation and
is usually identified in schwannoma, Verocay body-like
palisading can be seen in other neoplasms of variable
origin. Also referred to as a “rippled pattern” in certain
skin tumors 4, Verocay body-like palisading is reported
in trichoblastoma and sebaceoma, basal cell carcinoma,
dermatofibroma and dermatofibrosarcoma protuberans,
leiomyoma, palisaded encapsulated neuroma, perineuroma,
myofibroblastoma, melanocytic nevus, and malignant
melanoma 5. Basal cell carcinoma and adnexal tumors
can be distinguished by their relationship with epidermal/
adnexal structures and cytokeratin expression. Leiomyoma
shows positivity for markers of muscle differentiation and
no expression for S-100. Neural tumors are expected to be
positive with S-100. Melanocytic tumors show positivity
for melanocytic markers in addition to S-100 positivity. In
our case, conventional fibrohistiocytic areas neighboring
the Verocay body-like zone and the representative immunohistochemical profile made the diagnosis and no
further investigation was required.
Palisading histology is a rare pattern of dermatofibroma.
In two studies in which 200 dermatofibromas in one and 122 dermatofibromas in the other were examined
histopathologically, 2 of each were found to be the palisading
type (2% and 1.6% respectively) 6,7.
In conclusion, it is important to keep in mind that
dermatofibroma is one of the tumors that may form
Conflict of Interest
The authors declare no conflicts of interest.
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