Two cases of benign ﬁbrous histiocytomas
(dermatoﬁbromas) associated with
Langerhans cell histiocytosis
© 2017 John Wiley & Sons Ltd
We report two cases of ﬁbrous histiocytoma (FH)
associated with discrete nodular aggregates of
Langerhans cells (LCs) resembling Langerhans cell
histiocytosis (LCH). In addition, the LCs showed posi-
tivity for BRAF V600E immunohistochemistry, a ﬁnd-
ing reported in neoplastic but not reactive LCs.
our knowledge, these cases represent the ﬁrst pub-
lished association of FH and LCH.
A 71-year-old otherwise healthy male had a 10-
mm papule on his upper back excised. The histology
(Figure 1) showed a well-circumscribed dermal
tumour associated with overlying epidermal hyper-
plasia. The lesion was composed of histiocytic-like
and myoﬁbroblastic cells arranged in a haphazard
manner with a background of scattered mixed
inﬂammatory cells. Haemorrhagic areas, with hae-
mosiderin deposition and focal aneurysmal change,
were seen centrally. The features were those of FH of
conventional and focally aneurysmal subtype. How-
ever, a striking feature about this lesion was the
presence of intratumoural aggregates of histiocytoid
cells containing coffee bean-shaped nuclei with a
central nuclear groove. These cells were associated
with scattered eosinophils and showed focal exten-
sion into the epidermis, with smaller aggregates also
noted in the adjacent dermis. Immunohistochemistry
showed the cells to be positive for S100, CD1a and
Langerin, indicating LCs. Immunohistochemistry for
BRAF V600E was also positive in the LC population.
The ﬁnal histological diagnosis was, therefore, that of
FH associated with LCH. Chest radiograph and com-
puterised tomography (CT) scan showed no evidence
of further disease.
The second case was a 32-year-old man with a 15-
mm nodular lesion on his right buttock excised. His-
tology (Figure 2) showed a dense cellular spindle cell
proliferation of histiocytoid and myoﬁbroblastic cells
arranged in a haphazard manner. The spindle cells
intersected between collagen bundles at the periphery
of the lesion. Overlying epidermal hyperplasia was
evident. The features were those of a cellular FH.
However, also noted within the deeper aspect of the
lesion were large aggregates of histiocyte-like cells
with nuclear grooves associated with scattered eosi-
nophils. Immunohistochemistry conﬁrmed the popu-
lation to be LCs with positivity for S100, CD1a and
Langerin. BRAF V600E immunohistochemistry was
also positive in the LCs. The ﬁnal histological diagno-
sis was therefore that of a cellular FH associated with
LCH. There was no evidence of other cutaneous
lesions or systemic disease.
LCH-like proliferations have been described, often
occurring as an apparent exuberant inﬂammatory
response, in a variety of neoplastic and inﬂamma-
In relation to the skin, LCH-like
proliferations have been reported in arthropod bite
reactions, scabies and contact dermatitis.
regard to tumours, LCH and LCH-like proliferations
have been reported most commonly to be associated
with lymphoreticular malignancies.
In this setting,
LCH shows a complex relationship and may precede,
occur with or follow the disease.
Some cases of
LCH associated with leukaemia/lymphoma appear to
be derived from the same tumour stem cell.
example, identical T cell receptor (TCR) gene rear-
rangements have been demonstrated in LCH and T
cell lymphoblastic leukaemia/lymphoma.
synchronous development of LCH in the majority of
neoplasms appears to be unifocal and lacks progres-
sion, suggesting the process to be a localized reac-
Discrete LCH-like nodules in a
case of cutaneous B cell pseudolymphoma and a
case of Hodgkin’s lymphoma were found to be poly-
Both our cases demonstrated large nodules of an
LCH-like proliferation within FH; a ﬁnding not previ-
ously reported in the literature. Of interest, however,
are two previous case reports, by Soli et al. and Nakai
et al., of FH associated with indeterminate cells (ICs)
ICs are thought to represent a dis-
tinct stage of dendritic cell differentiation, with a sim-
ilar morphology and immunoproﬁle to LCs but
lacking Birbeck granules and Langerin staining.
morphological ﬁndings described in these two reports
were remarkably similar to those found in our cases.
However, the cell type differed, in that the absence of
Birbeck granules conﬁrmed the cell type to be ICs and
Solis et al. proposed possible pathogenetic
pathways for their ﬁndings, including the lesion rep-
resenting a collision tumour, occurring secondarily to
divergent differentiation from a single progenitor, or
as an indeterminate cell histiocytosis with involu-
tional ﬁbrosing changes resembling FH.
In our cases,
Histopathology 2018, 72, 878–888.