An African-American male, aged 60 years, presented
with a 2-month history of asymptomatic nodules on
his buttocks and thighs. On examination, there were
5 firm, nontender, subcutanteous nodules measuring approximately
1 cm x 0.5 cm without any overlying surface change.
There was no lymphadenopathy.
An excisional biopsy revealed lymphoplasmacytic inflammation
within a sclerotic collagenous background (Figure 1). The majority
of the cells had plasmacytic differentiation with kappa predominance
with mild hyperchromasia and pleomorphism. A B-cell
receptor gene rearrangement and flow cytometry did not reveal
monoclonality. The histologic differential diagnosis was plasmacytoma
vs B-cell non-Hodgkin's lymphoma, particularly extranodal
marginal zone lymphoma with plasmacytic differentiation.
A SPEP showed a small monoclonal component of IgG kappa.
A skeletal survey did not reveal any lytic lesions. A PET-CT of
the torso and pelvis revealed hypermetabolic activity of many
subcutaneous nodules primarily in the abdomen and pelvis. A
bone marrow biopsy and aspirate did not reveal multiple myeloma
or other hematological malignancies
The distribution on PET-CT, absence of bone marrow involvement,
and absence of lytic lesions were consistent with
a diagnosis of lymphoma. However, the absence of B-cell
monoclonality ultimately led to a diagnosis of extra-osseus
(extramedullary) plasmacytoma, which was additionally confirmed
by a consultation with hematology-oncology
The patient received partial clinical response with 4 cycles of
chemotherapy with bortezomib and dexamethasone.
Extramedullary plasmacytomas (EMPs) are rare soft tissue
plasma cell tumors without evidence of multiple myeloma at
other sites. Accounting for 3% of plasma cell neoplasms, EMPs
can be solitary, or rarely, multiple. The median age of presentation
is 60 years of age and 75% are male.
Extramedullary plasmacytomas in the skin are most commonly
asymptomatic, purple or flesh-colored nodules that can be either
superficial or deep in the soft tissue. Of all EMPs, 80% occur in
the head and neck and only 3% primarily involve the skin. Skin
involvement usually signifies widespread disease.
Solitary EMPs have a better prognosis than multiple EMPs. A
small series of 24 untreated individuals with at least solitary disease
showed a 40% survival rate at 10 years. However, survival
rates improve with treatment. In 18 patients with widespread
EMPs who were treated with chemotherapy, 50% had a complete
response and 33% had a partial response. The 10-year
survival of EMPs treated with chemotherapy remains unclear.
The authors have disclosed no relevant conflicts of interest.
- Lee SY, Kim JH, Shin JS, et al. A case of extramedullary plasmacytoma arising
from the posterior mediastinum. Korean J Intern Med. 2005;20(2):173-176.
Address for Correspondence