Discussion:
Plasmacytomas are immunoproliferative, monoclonal tumors of the β-cell
line and are classified as non-Hodgkin‘s lymphoma. Extramedullary
plasmacytomas present as a localized mass lesion. About 75% of them
occur in the upper respiratory tract and also they may occur in a
variety of anatomic sites [2,4]. The differential diagnoses of
extramedullary plasmacytoma include reactive lesions with an abundance
of plasma cells, lymphomas with marked plasma cell differentiation.
Distinction from lymphoma with extreme plasma cell differentiation may
be problematic[5]. Lymphoplasmacytic lymphoma, immunoblastic or
plasmablastic large cell lymphomas, and especially MALT may be
misdiagnosed as plasmacytoma[6,5]. Moreover, the distinction of
extramedullary plasmacytoma from both solitary plasmacytoma of the bone
and multiple myeloma is sometimes very difficult.
Mayoclinic diagnostic criteria for solitary plasmacytoma include 1)
biopsy-proven solitary lesion of bone or soft tissue with evidence of
clonal plasma cell,2) normal bone marrow with no evidence of clonal
plasma cells, 3) normal skeletal survey,4) absence of end-organ damage
such as anemia, hypercalcemia, renal failure or additional lytic bone
lesions,5) low or absent serum or urinary level of monoclonal
immunoglobulins[5].
In the present case, a systemic workup for finding dissemination of
tumor cells including bone marrow aspiration, skeletal radiographic
survey, complete blood count, serum biochemistry analysis, and
monoclonal immunoglobulin levels of serum and urine did not reveal
evidence of spread and the sphenoid sinus was the sole site of tumor.
Therefore, extramedullary plasmacytoma of the sphenoid sinus was
confirmed in this clinical case.
Based on the literature review, extramedullary plasmacytomas limited to
the sphenoid sinus are extremely rare. It was estimated that only 1.6 %
of extramedullary plasmacytomas arise from the sphenoid sinus that
concluded approximately 15 cases until 2013. Moreover, in the localized
sphenoid sinus tumor, the symptoms are usually non specific. when the
tumor extended, visual loss, diplopia and, facial pain can be presented.
[7, 8] Humphrey et al [9] reported an extramedullary
plasmacytoma of the sphenoid sinus that presented with isolated
VIth-nerve paralysis. In our presented case progressive ocular muscle
paralysis and ptosis were the clinical manifestations. Orbital
space-occupying lesions presenting with painful ophthalmoplegia are
mostly due to malignancies that may originate from inside or outside of
the globe [10]. In our case, the sphenoid originated tumor extended
to the right orbital globe. Ampil et al [11] reported cavernous
sinus involvement by extramedullary plasmacytoma of the sphenoid sinus
which presented with retro-orbital headache. CT-angiography in our case
showed cavernous sinus involvement and the patient‘s first complaint was
headache 3 months earlier to admission.
The typical treatment for extramedullary plasmacytoma is local
radiation, usually with radiotherapy in the range of 40 to 50
Gy[12]. Galieni et al [12] suggested that surgical removal of
solitary extramedullary plasmacytoma could be performed for small masses
and as secondary therapy after failure of local irradiation in the
elimination of mass. Miller et al [13] reported a case of sphenoid
sinus plasmacytoma that was treated with radiation 6400 cGy.
Chemotherapy has not been successful in extramedullary plasmacytoma
treatment but Wein et al [14] treated a patient with sphenoclival
plasmacytoma with systemic chemotherapy. Surgical resection of tumor by
endonasal transsphenoidal approach with complementary radiotherapy was
performed for our patient. After 6 months of follow-up, there have been
some improvements in the clinical symptoms of the patient. Although,
paresis of ocular muscles is somewhat resolved, decreased visual acuity
still exists. Hardwood et al [15] reported two cases of radiotherapy
failure in the treatment of solitary extramedullary plasmacytoma which
one of them was in the sphenoid sinus. With this in mind, 10-year
disease-free survival rates are reported to be 70-80% [5], further
follow-up with greater care is required for our patient.