SHM Converge Scientific Abstract ePoster Gallery-A Case of Crab as a Red Herring

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This case report describes a 69-year-old woman who presented with progressive bilateral leg pain, fatigue, weight loss, constipation, polyuria, and dry cough. Initial findings of hypercalcemia, mild renal dysfunction, anemia, and lytic bone lesions suggested multiple myeloma, especially given the classic “CRAB” pattern (calcium elevation, renal dysfunction, anemia, bone lesions). However, further evaluation showed a much broader picture.<br /><br />Despite a normal mammogram within the past year and no palpable breast mass, imaging revealed diffuse pulmonary nodules, enlarged intrathoracic lymph nodes, and extensive liver metastases. Serum protein electrophoresis was polyclonal rather than consistent with myeloma, and tumor markers were not diagnostic. Liver biopsy ultimately showed poorly differentiated carcinoma positive for pankeratin, CK7, mammaglobin, and CK19, confirming metastatic breast cancer. The final diagnosis was stage IV triple-negative breast cancer.<br /><br />The report highlights important clinical lessons. First, CRAB findings are not specific to multiple myeloma and can also occur in metastatic breast, lung, or prostate cancer. Second, mammography can miss a substantial proportion of breast cancers, particularly in women with dense breast tissue. Interval cancers—those appearing after a normal screening mammogram—are often higher grade and associated with worse outcomes. Digital breast tomosynthesis may improve detection in dense breasts.<br /><br />The patient was treated for hypercalcemia and discharged with rapid oncology follow-up. Given her poor functional status and advanced disease, she and her family chose hospice instead of chemotherapy.<br /><br />Overall, the case emphasizes the need for a broad differential diagnosis when evaluating cancer-like syndromes, early oncology involvement, and careful attention to goals of care in patients with newly diagnosed advanced malignancy.

Asset Subtitle

Tommy T. Chiou

Meta Tag

Author List Brian Ji, Catherine E. Firestein, Harshal Mehdi, Hemali Batra-Sharma, Maryann T. Ally, Tommy T. Chiou

Category Clinical Vignettes

Concept CRAB Findings

Concept Tissue Diagnosis

Concept Malignancy Differential Diagnosis

Concept Mammography

Concept Metastatic Cancer

Distinguished Non-Finalist

Presenter Organization UCSD School of Medicine

Presenting Author Tommy T. Chiou

Track Adult

Keywords

multiple myeloma

CRAB syndrome

hypercalcemia

metastatic breast cancer

triple-negative breast cancer

lytic bone lesions

mammography limitations

dense breast tissue

liver metastases

palliative care

CRAB Findings

Tissue Diagnosis

Malignancy Differential Diagnosis

Mammography

Metastatic Cancer