Paget's disease

Two distinct disorders: one is a focal bone remodeling disease (excessive osteoclast and chaotic osteoblast activity) leading to structurally weak, deformed bone; the other is an eczematous, ulcerative lesion of the nipple caused by malignant cells (Paget cells) infiltrating the epidermis, usually from an underlying breast carcinoma.

• As older adults can develop Paget's disease of bone (~1–3% > age 55), it's a notable cause of bone pain, deformity, and fracture, with rare (<1%) sarcomatous transformation. Paget's of the breast is rare (1–4% of breast cancers) but crucial to catch, as it almost always signifies underlying DCIS or invasive cancer that needs prompt treatment.

• Paget disease of bone: Usually affects older adults (>50). Many cases are asymptomatic, found via high alkaline phosphatase on labs or incidentally on X-ray. Symptomatic patients have deep, aching bone pain (often pelvis, spine, skull, or long bones), bony deformities (e.g. enlarged skull, bowed legs), and pathologic fractures. Skull involvement may lead to hearing loss (due to nerve compression).
• Paget disease of breast: Typically presents in middle-aged or older women with a unilateral nipple and areolar rash that is red, scaly, and may bleed or ooze. Patients often report burning, itching, or pain in the area. The nipple can become flattened or retracted. Crucially, the skin changes don't improve with topical treatments (unlike eczema).

1. For an older patient with suspected Paget's (e.g. elevated ALP or localized bone pain/deformity), get targeted X-rays of the suspicious areas. X-ray findings (mixed lytic and sclerotic lesions, cortical thickening) confirm the diagnosis; a bone scan can map the full extent of metabolically active disease.
2. Check serum alkaline phosphatase (often markedly elevated) with normal calcium and phosphate; this reflects high bone turnover. If Paget's is strongly suspected and ALP is normal, consider bone-specific ALP or other turnover markers. Biopsy is usually not needed unless a complication (like sarcoma) is suspected.
3. For any persistent nipple eczema or ulcer (especially unilateral), insist on a skin biopsy of the nipple lesion. Histology will show large Paget cells (malignant intraepidermal glandular cells), confirming the diagnosis. This should prompt evaluation of the breast tissue with imaging (mammography ± MRI) to look for underlying DCIS or an invasive tumor.

1. Paget's disease of bone: Bisphosphonates (e.g. IV zoledronate) are first-line to slow bone turnover and relieve symptoms. Ensure adequate calcium/Vit D to prevent hypocalcemia. Second-line: Calcitonin (if bisphosphonates are contraindicated) can help reduce pain. Use NSAIDs/analgesics for pain. Orthopedic surgery is reserved for complications (e.g. fracture fixation, joint replacement for severe arthritis, or decompression for spinal stenosis).
2. Paget's disease of the breast: the mainstay is surgical treatment of the underlying cancer. Depending on extent, either mastectomy (complete breast removal) or breast-conserving surgery (removal of nipple-areola and tumor, with post-op radiation) is performed. If invasive cancer is present, manage as breast cancer: check lymph nodes and add appropriate adjuvant therapy (radiation for DCIS; chemotherapy and/or hormonal therapy if invasive, based on tumor markers and stage).

• Paget's bone = high ALP, normal Ca in an older patient with bone pain (classic lab clue — unlike bone metastases or hyperparathyroidism). Also remember an increasing hat size or new hearing loss in an elderly patient can be a tip-off for Paget's disease of bone.
• Paget's breast = nipple rash that won't heal. Any unilateral "ecema" of the nipple that doesn't respond to treatment should raise concern for Paget's disease (underlying cancer).

• Paget's bone: Sudden new severe pain or a soft tissue mass at a known pagetic site → suspect osteosarcoma (malignant transformation, <1% cases). Also watch for spinal cord compression signs (weakness, sensory loss, incontinence) in spinal Paget's, which require urgent decompression.
• Paget's breast: Persistent unilateral nipple lesion is itself a red flag — biopsy it to exclude Paget's (and underlying cancer). Remember, >80% of mammary Paget cases have an underlying DCIS or invasive carcinoma, so missing this diagnosis delays essential cancer treatment.

1. Paget bone: Older patient with bone pain or high ALP → X-ray the suspicious region (looking for Paget changes).
2. If X-ray confirms Paget's → get bone scan to determine disease extent; check baseline ALP level.
3. Treat active/symptomatic disease with bisphosphonate (e.g. single IV zoledronate); monitor ALP for response.
4. Paget breast: Patient with chronic nipple eczema → biopsy the lesion to confirm Paget's (Paget cells on pathology).
5. If Paget's is confirmed → perform breast imaging (mammogram ± MRI) to detect underlying tumor; evaluate lymph nodes if invasive cancer is found.
6. Treat with appropriate surgery (mastectomy or central lumpectomy) + adjuvant therapy as needed (radiation for DCIS; add chemo/endocrine therapy if invasive).

• Elderly man with long-standing hat no longer fits (skull enlargement), hearing loss, bone pain, and isolated very high alkaline phosphatase → Paget disease of bone. X-ray may show thickened, disorganized bone with mixed lytic/sclerotic areas (e.g. "cotton wool" skull spots).
• Postmenopausal woman with a unilateral itchy, scaly nipple lesion that persists for months despite creams → Paget disease of the breast. This usually signifies an underlying ductal carcinoma in situ (DCIS) or invasive breast cancer, even if no breast mass is felt.