Journal of the Louisiana State Medical Society
C linical C ase of the M onth
A 63-Year-Old Woman With Rash and Proximal Muscle Weakness
Vaughan Washco, DO; Ross McCarron, MD; Lee S. Engel, MD, PhD; Sanjay Kamboj, MD; Fred A. Lopez, MD
A 63-year-old woman with a history of infiltrating ductal breast cancer, status post-mastectomy and chemo- therapy, was in remission for 18 months prior to being admitted to the hospital with complaints of a pruritic erythematous macular rash involving her head, chest, and bilateral upper and lower extremities. Along with the dermatologic manifestations, physical exam revealed proximal symmetrical muscle weakness and bilateral axillary lymphadenopathy. Initial workup for muscle weakness revealed a creatine kinase of 2,200 IU/L (normal 20-180 IU/L). After administration of intravenous fluids for renal protection, serum sodium dropped to 121 mEQ/L (normal 135-145 mEQ/L). Computed tomography of the chest showed axillary and supraclavicular lymphadenopathy. Biopsy of a supraclavicular node revealed infiltrating ductal cancer with histologic and morphologic characteristics similar to her previous breast cancer. Following an extensive laboratory workup, we concluded that our patient’s myositis and hyponatremia were paraneoplastic syn- dromes secondary to her recurrent breast cancer.
CASE PRESENTATION A 63-year-old woman with a history of hypertension, hypothyroidism, and stage IIB poorly differentiated infil- trating ductal breast cancer (hormone receptor and Her2/ neu negative) that had been in remission for 18 months following left mastectomy and chemotherapy presented to the emergency department with an acute pruritic ery- thematous macular rash (Figure 1). The rash had progres- sively worsened over the past three weeks and involved her head, chest, and bilateral upper and lower extremities. Associated symptoms included worsening fatigue, body cramps, and muscle weakness. Along with this rash, sym- metrical proximal muscle weakness and bilateral painless axillary lymph node enlargement were noted on physical exam. A rheumatologic panel revealed a positive ANA. She was negative for Anti-SSA/SSB, Anti-DNA, Anti-sm, Anti-nRNP, Anti-Jo-1, Anti-histone, and Anti-Scl-70. Hepa- titis panel was also negative, and complement C3 and C4 levels were normal. Creatine kinase (CK) was elevated at 2200 IU/L (normal 20-180 IU/L). She had no recent his- tory of new medications known to cause an elevated CK, nor recent trauma, ethanol, or illicit drug use. Based on the new onset of rash, proximal muscle weakness, and elevated CK, a clinical diagnosis of dermatomyositis was suspected.
Shortly after initiation of intravenous fluids for renal pro- tection, serial metabolic panels revealed hyponatremia at a level as low as 121 mEQ/L (normal 135-145 mEQ/L). The patient was in a euvolemic state, with normal kidney and liver function studies, and had no signs or symptoms to suggest heart failure. Serum osmolality was 260 mOsm/ kg (normal 275-295 mOsm/kg), urine osmolality was 674 mOsm/kg (normal 50-1200 mOsm/kg), urine sodium was 155 mEQ/L, and TSH was 1.78 IU/ml (normal 0.40-4.00 IU/ml). She was not on any medications known to cause antidiuretic hormone release, and there were no clinical features to suggest adrenal insufficiency. With the above findings, the cause of hyponatremia was determined to be SIADH. The hyponatremia improvedwith fluid restriction. Concern for an underlyingmalignant process prompted a computed tomography scan (CT) of the chest, which revealed bilateral axillary and supraclavicular lymphade- nopathy (Figure 2). A biopsy of her supraclavicular lymph node confirmed the diagnosis of a high-grade carcinoma, which was hormone receptor and Her2/neu-negative like her previous cancer and shared the same histologic mor- phology. MRI of the brain did not demonstrate metastatic disease. Skin biopsy was negative for malignant cells but revealed inflammatory changes characteristic of dermato- myositis (Figure 3).
268 J La State Med Soc VOL 166 November/December 2014
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