International Journal of Clinical Medicine, 2013, 4, 1-4
Published Online December 2013 (http://www.scirp.org/journal/ijcm)
http://dx.doi.org/10.4236/ijcm.2013.412A1001
Open Access IJCM
1
IgG4-Related Disease Presenting as a Soft Tissue Tumor
Affecting Skeletal Muscle: A Case Report
David Sáez Martínez1, Felipe López Oliva1, María Jesús Fernández Aceñero2,
Elena Fontoira Moyer3, Juan Luis Arranz Cozar4
1Ortrhopedic Surgery Department, Fundación Jiménez Díaz, Madrid, Spain; 2Pathology Department, Fundación Jiménez Díaz, Mad-
rid, Spain; 3Radiology Department, Fundación Jiménez Díaz, Madrid, Spain; 4Oncology Department, Fundación Jiménez Díaz, Mad-
rid, Spain.
Received October 30th, 2013; revised November 28th, 2013; accepted December 15th, 2013
Copyright © 2013 David Sáez Martínez et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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ABSTRACT
Background: IgG4-related disease is a systemic lymphoproliferative syndrome that shows IgG4-producing plasma cell
expansion in affected organs with fibrotic or sclerotic changes. The lacrimal glands, salivary glands and pancreas are
typically affected. We report a case of IgG4-related disease presenting a soft tissue tumor affecting skeletal muscle.
Case Report: A 32-year-old man presented a soft tissue mass in his left arm. Magnetic resonance imaging revealed a
spindle like, peripheral mass, in the lateral head of the triceps of his left arm. Tru-Cut Biopsy provided the diagnosis of
IgG4-related disease affecting skeletal muscle. Glucocorticoid treatment was effective. Conclusion: To our knowledge,
this is the first reported case of IgG4-related disease affecting skeletal muscle and presenting a soft tissue mass.
Keywords: IgG4-Related Disease; Soft Tissue Mass; Skeletal Muscle
1. Introduction
Immunoglobulin G4-related disease (IgG4-RD) is an
increasingly recognized lymphoproliferative syndrome of
unknown etiology. Patients show tumor-like swelling of
involved organs, lymphoplasmacytic and IgG4 producing
plasma cells infiltrating and affected organs with fibrotic
or sclerotic changes. Elevated serum concentrations of
IgG4 are found in 60 % of pat ie nt s wi t h Ig G4 -R D.
The lacrimal glands, salivary glands and pancreas are
the major affected organs.
Another feature of IgG4-RD is good glucocorticoid
responsiveness.
We report the first case to our knowledge of IgG4-RD
presenting a soft tissue tu mor affecting skeletal muscle in
the arm.
2. Case Report
A 32-year-old man was referred to our institution pre-
senting a soft tissue mass in his left arm.
He had a medical history of asthma, left hypertrophic
pachymeningitis and an orbital pseudotumor waiting for
surgery.
Physical examination found a hard, nontender and
mobile mass, with well defined borders, in the lateral
aspect of his left arm, measuring 3 × 3 cm in size. It
showed mild growing during the last two years. Tinel
Test was negative. He also presented a right exophthal-
mos.
Complete blood count and serum chemistry, including
IgG levels (787 mg/dl), were all within their normal lim-
its (Table 1).
The MRI described a spindle like, peripheral mass, in
the lateral head of the triceps, with well demarcated bor-
ders, T1 and T2 hyperintense and hypercaptant with con-
trast. It had a central hypointense region in all seq uences
that could correspond to fibrosis. It measured 2 cm × 17
mm × 2.5 cm (Figure 1).
An ultrasound guided Tru-Cut Biopsy was performed,
referring 4 cylinders of material to Soft Tissue Pathology
Department. The biopsy showed a fibro inflammatory
condition, with abundant plasma cells, dissecting and

IgG4-Related Disease Presenting as a Soft Tissue Tumor Affecting Skeletal Muscle: A Case Report 2
Table 1. Regular laboratory results.
Parameter Value Units
Erythrocytes (RBC) 4.21 *106/mm3
Hematocrit 43.2 %
White blood cell count 9.60 *103/mm3
Segmented neutrophils 78.7 %
Lymphocytes 9.9 %
Monocytes 9.5 %
Eosinophils 1.2 %
Basophils 0.7 %
INR 1
Platelet count 163 *103/mm3
Fibrinogen 416 mg/dl
Creatinine, serum 1.04 mg/d l
Gamma glutamyl transferase (GGT) 17 U/l
Glucose 99 mg/d l
Lactate dehydrogenase serum (LDH) 4 mEq/ l
Potassium 140 mEq/l
Sodium serum 74 mg/d l
Triglyceride 5.3 mg/dl
Uric acid
Erythrocy te sedimenttion rate 2 mm/h
IgG serum 787 mg/dl
IgA serum 92.8 mg/d l
IgM serum 51 mg /dl
Figure 1. (A)-(C) Magnetic resonance images showed a well defined peripheral mass in the lateral head of the triceps hyper
ntense and hypercaptant with contrast. i
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IgG4-Related Disease Presenting as a Soft Tissue Tumor Affecting Skeletal Muscle: A Case Report 3
infiltrating the skeletal muscle, causing degeneration and
atrophy of muscular cells. Immunohistochemical analysis
using CD 38 marker (plasma cell marker) and IgG4 stain
revealed an increased IgG4 (+) plasma cell count (Figure
2).
Surgical treatment of his orbital pseudotumor was
done. The biopsy of the orbital lesion showed an inflam-
matory pseudotumor. The so ft tissue mass in his arm had
a very good responsiveness to glucocorticoid treatment
initiated after the neurosurgical procedure, reducing its
size so no surgical treatment of the arm mass was indi-
cated.
Based on the histopathological and immunohisto-
chemical findings a diagnosis of IgG4-related disease
affecting skeletal muscle was made.
3. Discussion
Soft tissue tumors are heterogeneous disorders, being the
vast majority benign. They are most commonly charac-
terized histologically according to the type of tissue they
resemble. Unfortunately both benign soft tissue tumors
and soft tissue sarcomas have a similar presentation.
While clinical and imaging features will help guide an
appropriate work-up, any suspicious soft tissue mass
Figure 2. Histopathological Findings. (A)-(C) Sections of the lesion show a fibroinflammatory condition affecting the skeletal
muscle (A, H & E, ×100. B, H & E, ×200. C, H & E, ×400). (D) Desmin stain ×100 positive for skeletal muscle. (E) CD 38
marker positive indicating plasma cell infiltration. (F) IgG4 stain positive revealed an increased IgG4 plasma cell count.
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IgG4-Related Disease Presenting as a Soft Tissue Tumor Affecting Skeletal Muscle: A Case Report 4
must be biopsied [1].
IgG4-RD is a novel lymphoproliferative syndrome of
unknown etiology including a collection of disorders that
share clinical and pathological characteristics. Several of
the manifestations can occur in the same patient and
comprise: Type 1 autoinmune pancreatitis and IgG4-re-
lated sclerosing cholangitis, inflammatory orbital pseu-
dotumor, retroperitoneal fibrosis, thyroiditis, and other
sclerosing or IgG4-related disorders as dacryoadenitis,
sialadenitis, aortitis and periaortitis, interstitial pneumo-
nitis, tubulointerstitial nephritis, hypertrophic pachyme-
ningitis [2].
The principal symptoms and signs of IgG4-RD are a
slow growing mass or diffuse enlargement of an organ.
To our knowledge this is the first reported case of local-
ized IgG4-related disease affecting skeletal muscle and
presenting as a soft tissue tumor. IgG4-RD can also pre-
sent with clinical findings related to affected organs with
fibrotic or sclerotic changes [2].
Pathologically the disease is characterized by IgG4
positive plasma cells and lymphocytes tissue infiltration
which may be accompanied by sclerosis. Elevated serum
levels of IgG4 may be present, being an important aid in
diagnosis, although they are not diagnostic [3].
The diagnosis of IgG4-RD is made with biopsy find-
ings demonstrating t he characterist ic hist opathology . Core-
Needle Biopsy or Tru-Cut Biopsy is most often indicated
for superficial or accessible deep extremity soft tissue
tumors that are of sufficient size to n eedle placement (>3
cm) [1]. In our case this was the technique of biopsy in-
dicated. A good therapeutic response to glucocorticoids
is also characteristic of IgG4-RD, by symptomatic and
organ function improvement or reductions in the size of
masses, as it happened in our case [4,5].
Glucocorticoid therapy has been suggested as the ini-
tial treatment of IgG4-RD. Azathioprine, mycophenolate
mofetil and rituximab have been used to treat resistant
patients [5,6].
The natural history and prognosis of IgG4-related dis-
ease are not well described. Despite that good respon-
siveness to glucocorticoid treatment, relapses are com-
mon and organ dysfunctio n may arise from inflammato ry
and fibrotic changes. The possibility of increased risk of
malignancy is not clear [5,6].
4. Conclusion
Despite its extreme rarity, IgG4-related disease may be
presen ted as a sof t tissue tu mor affecting skeletal muscle.
Biopsy may be the only diagnostic procedure. A good
therapeutic response to glucocorticoids should be ex-
pected.
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