Discussion
Myositis identifies a group of patients in whom muscular weakness is the
principal clinical feature often associated with muscle pain,
tenderness, wasting, or other forms of connective tissue diseases; the
muscle biopsy generally demonstrates areas of muscle fiber necrosis
accompanied by interstitial and/or perivascular cellular infiltrates.1
Its incidence is estimated to be around 4.27–7.89 cases per 100,000
people per year.5 Inflammatory myositis (IM) is
broadly classified into five categories: polymyositis, dermatomyositis,
immune-mediated necrotizing myopathy, sporadic inclusion body myositis,
and overlap myositis.6 Clinically, a patient can
present with acute or subacute-onset muscle weakness of different
patterns, often accompanied by raised creatinine kinase
(CK).7
In severe cases, respiratory and oesophageal muscles can be
affected.8 The diagnosis of inflammatory myositis (IM)
requires careful clinical evaluation paired with serological markers,
neurophysiological testing, and a muscle biopsy. In history taking, we
need to take a relevant family history, myopathic drugs, alcohol, and
features of endocrinopathy.9
Myositis associated with overlap syndromes is usually of paroxysmal
variety and has been associated with one or another of connective tissue
disorders.1 Raised serum creatine kinase is found to
correspond with underlying myositis in patients with SLE.12Furthermore,
the presence of myositis-specific antibodies such as anti-U1RNP,
anti-Ro/SSA, anti-La/SSB, anti-Sm or anti-PM-Scl is suggestive of an
overlap
myositis.13,12Myositis, lymphocytic vasculitis, type II muscle, atrophy, vessel wall
thickening, and vacuolar myopathy are various histopathological findings
observed in the muscle biopsies of patients with
SLE.14However, histopathological findings of lymphocytic vasculitis and/or
myositis are confirmatory of true myositis in
SLE.12
SLE is an autoimmune disease that affects virtually any organ in the
body. It affects females more commonly than males.4 Skeletal muscle
complications are common in SLE patients, which are seen in the form of
myalgia, muscle weakness, and atrophy.15 Myalgia is the most skeletal
muscle manifestation, affecting 40–80% of
patients.16
Treatment can prove difficult, as both conditions respond to a variety
of immunosuppressive and cytotoxic agents. Corticosteroids were used as
first-line therapy, and additional immunosuppressive agents such as
cyclophosphamide, methotrexate, rituximab, and mycophenolate mofetil
have been used with varying degrees of clinical response and remission
rates.13,17
The reports on the prognosis of SLE-myositis overlap syndrome are
conflicting. Some of them suggest that it follows a benign course, while
others suggest no difference between them in terms of morbidity and
response to
therapy.13,18 Again, another study suggests that those with SLE-myositis overlap
syndrome have a poorer outcome with early
death.14 Although myositis in SLE responds well to corticosteroids, the
association of pulmonary involvement leads to early mortality with an
increased standardized mortality ratio compared to SLE alone. This
indicates a poor prognosis for SLE-myositis overlap syndrome.19
Our patient was initially diagnosed with polymyositis 2 years ago after
she presented with characteristic proximal muscle weakness and
difficulty swallowing with associated multiple joint pain, and
laboratory investigations revealed elevated CK-total (2227 IU/L) and
anti-PM scl-75 (elevated). With an initial treatment with
corticosteroids and a continual treatment with azathioprine, the patient
showed symptomatic improvement. After 2 years of treatment, she presents
with a history of worsening joint pain, a decreased amount of urine, a
cola-colored change of urine, and bilateral flank pain. Physical
findings showed elevated blood pressure of 170/90 mm hg, pale
conjunctiva, and bilateral costovertebral angle tenderness. Laboratory
investigations showed moderate anemia (Hgb of 9.2 g/dl), positive ANA
qualitative study, total CK 2154 IU/L (more than 15x elevated), elevated
serum creatinine level (7 mg/dl), decreased C3 level (0.275 g/dl),
normal C4 (0.275 g/dl), and elevated anti-dsDNA Ab (141.7 IU/L).
Considering the evidence, she was diagnosed with SLE-polymyositis
overlap syndrome, and she was started on methylprednisolone 500 mg IV
for 3 days, followed by prednisolone 60 mg oral daily, cyclophosphamide
750 mg IV monthly, and amlodipine 10 mg oral daily. At the
4th month of induction therapy with methylprednisolone
and cyclophosphamide, her creatinine normalized and her proteinuria
resolved. The patient is currently on maintenance therapy with
azathioprine, chloroquine, and low-dose prednisolone, with complete
clinical and laboratory remission.
In our patient, the occurrence of myositis, or polymyositis in our case,
before SLE makes it unique and to the best of my knowledge, this pattern
of clinical presentation has never been reported before.