Figure 1: Erythematous macular rash of the face (A), arms (B), and legs (C).
Prior to discharge, she was started on high-dose pred- nisone, which mildly improved her skin lesions andmuscle weakness. Shortly after discharge, she followed up with oncology and chemotherapy consisting of carboplatin and gematabine was initiated. After several cycles of chemo- therapy, positron emission tomography showed progression of metastatic lymphadenopathy with new hypermetabolic retroperitoneal lymph nodes. Several months later, her symptoms of muscle weakness progressively worsened along with her performance status, and she passed away while under the care of home hospice. DISCUSSION Paraneoplastic syndromes associatedwith breast cancer are uncommon. There have been several reports that discuss myositis associated with breast cancer 1-3 and a few cases of SIADH associated with breast cancer. 4-7 To our knowledge, this is the first report describing SIADH and dermato- myositis simultaneously as paraneoplastic syndromes with recurrent breast cancer. Occurrence of these concurrent paraneoplastic syndromes in recurrent breast cancer is rare, and therefore, we can only speculate about their prognostic impact on staging or treatment of recurrent malignancy. Myositis associated with malignancy includes derma- tomyositis and polymyositis. Dermatomyositis presents with proximal muscle weakness and skin changes with classic findings of a heliotrope rash and gottron papules. 8 The pathophysiology of dermatomyositis associated with cancer is not clearly understood; however, it is likely multi- factorial. The main contributing factor is thought to be an immune system imbalance with a failure in immunological surveillance. 8-10 Polymyositis and dermatomyositis associ- ated with malignancy typically occur in adults, with an incidence peak from age 40 to 60 years. In 60% of cases, they precede the clinical onset of neoplasm. Lung, prostatic, and gastrointestinal cancers are the most frequently associated neoplasms in men, while breast and gynecological cancers
are most often associated in women. 11 The Bohan and Pe- ter criteria are most widely used to make the diagnosis of dermatomyositis. 12 These criteria take into consideration the physical findings of symmetrical proximal muscle weak- ness, elevated skeletal muscle enzyme levels, myopathic changes on electromyography, and skin lesions characteris- tic of dermatomyositis. Meeting all four of the above criteria indicates a definite diagnosis, three out of four a probable diagnosis, and two out of four a possible diagnosis of dis- ease. 12 Skin and muscle biopsy is also helpful in making the diagnosis, with hallmark features of peri-fascicular atrophic regeneration, degenerating myofibers, and the presence of perivascular inflammation in the muscle. 13 Treatment of this paraneoplastic syndrome is directed towards the underly- ing cancer. However, as seen in our patient, steroids have been shown to provide some symptomatic relief. If there is a poor response to steroids, immunomodulating therapy may be warranted. 8 Paraneoplastic SIADH arises from tumor cell produc- tion of antidiuretic hormone and atrial natriuretic peptide. Antidiuretic hormone leads to increased free-water reab- sorption, whereas atrial natriuretic peptide has natriuretic and antidiuretic properties. These combined actions lead to a hypoosmotic, euvolemic hyponatremia. Common symp- toms are nonspecific and include muscle cramps, lethargy, nausea, vomiting, gait disturbances, seizures, and altered mental status. 8,14,15 SIADH affects 1% to 2% of all patients with cancer, with small cell lung cancer accounting for most of these cases. 8 SIADH rarely occurs in breast cancer. 4-7 The diagnosis is one of exclusion and includes a euvolemic state, low serum osmolarity, and a urine osmolarity greater than appropriate considering the plasma tonicity. Before mak- ing the diagnosis, it is essential to rule out other causes of euvolemic hyponatremia such as hypothyroidism, adre- nal insufficiency, primary polydipsia, or drug-associated anti-diuretic release. 14-15 The mainstay treatment of mild to moderate hyponatremia in SIADH is water restriction. 8,15 Five hundred to 1,000 ml of free water restriction per day
J La State Med Soc VOL 166 November/December 2014 269
Made with FlippingBook - Online catalogs