| Subtype / synonyms | Immunoglobulin product | Typical demographic and organ sites | Hallmark phenotype / pathology | Diagnostic signature | Treatment | Prognosis / statistics |
|---|---|---|---|---|---|---|
| **α-heavy-chain disease (α-HCD); immunoproliferative small intestinal disease (IPSID); Mediterranean lymphoma** | Truncated monoclonal **IgA heavy chain** without associated light chain (pqac-00000008, pqac-00000006) | **Approx. historical case count:** **>400** reported since 1968; most prevalent in **2nd-3rd decades**, slight male predominance; mainly **Mediterranean, North African, Middle Eastern** populations of low socioeconomic background; primarily **proximal small bowel (duodenum/jejunum)**, rarely respiratory tract (pqac-00000008, pqac-00000006) | Malabsorption syndrome with **weight loss, diarrhea, abdominal discomfort**, growth retardation, amenorrhea, alopecia; advanced disease may show **ascites/anasarca**. Histology is **extranodal marginal zone/MALT lymphoma** with lamina propria **lymphoplasmacytic infiltrate**, villous atrophy, ± lymphoepithelial lesions; associated bowel infection by **Campylobacter jejuni** or **Helicobacter pylori** may occur (pqac-00000008, pqac-00000006) | Serum electrophoresis may be normal, hypogammaglobulinemic, or show a broad band in **α2/β** region; **anti-IgA immunofixation positivity is mandatory**; abnormal α chains may be found in jejunal/gastric fluids or small amounts in urine; endoscopy often shows **infiltrative or nodular** proximal small-bowel lesions (pqac-00000006, pqac-00000007) | Eradicate documented GI infection; empiric **metronidazole, ampicillin, or tetracycline** often used for **6 months**. Refractory disease: **total abdominal radiation** or doxorubicin-containing chemotherapy (**CHOP, CHVP, ABV**); surgery mainly for complications (pqac-00000007, pqac-00000005) | **33-71%** of early-stage patients achieve clinical/laboratory/histologic remission with antimicrobials, but recurrences are frequent. Multi-drug chemotherapy: **64% complete remission**, **67% 5-year overall survival**. Untreated disease can progress locally then systemically; fatal complications include obstruction, perforation, intussusception, malnutrition/cachexia, infection (pqac-00000007, pqac-00000005) |
| **γ-heavy-chain disease (γ-HCD); Franklin disease** | Truncated monoclonal **IgG heavy chain** without associated light chain (pqac-00000008, pqac-00000007) | **Approx. historical case count:** **~130** reported; age at diagnosis **51-68 years** with **female predominance**; common sites include **bone marrow, spleen, lymph nodes**, and extranodal sites such as **skin, thyroid, salivary glands, GI tract, conjunctiva** (pqac-00000008, pqac-00000007) | Often linked to **lymphoplasmacytic neoplasm** (**83-91%**); **25%** have autoimmune disease (especially rheumatoid arthritis). Clinical patterns include disseminated lymphoma with constitutional symptoms (**57-66%**), generalized lymphadenopathy/splenomegaly/hepatomegaly (**50%**), or localized medullary/extramedullary disease (~**25%**). Histology is heterogeneous with mixed lymphocytes, plasmacytoid lymphocytes, plasma cells, sometimes immunoblasts/eosinophils/histiocytes and occasional Reed-Sternberg-like cells (pqac-00000008, pqac-00000006, pqac-00000007) | Serum electrophoresis may be normal or show a **β-region monoclonal band**; **anti-IgG immunofixation positivity without light chains is mandatory**. Abnormal γ chains are often detectable in **urine** due to low molecular weight/dimerization. Lab clues include cytopenias, Coombs-positive hemolysis, thrombocytopenia, circulating plasmacytoid cells/plasma cells (pqac-00000006, pqac-00000007) | Management tailored to symptoms, autoimmune disease, and lymphoma burden. Options include **chlorambucil**, **melphalan + prednisone**, **bortezomib + prednisone**, **rituximab** for CD20+ disease; **CHOP ± rituximab** for aggressive/refractory cases; **fludarabine + rituximab** reported effective in pancytopenic disease. Localized extranodal disease may be treated with surgery or radiation; asymptomatic patients without lymphoma may be observed (pqac-00000005, pqac-00000007) | Course is heterogeneous. Some patients without overt lymphoma have **spontaneous remissions** and prolonged survival without treatment; treated localized lymphoma often reaches sustained complete remission. Systemic lymphoma may be aggressive or indolent. **Median survival 7.4 years** (range **1 month to >2 decades**) in the Mayo series (pqac-00000005, pqac-00000007) |
| **μ-heavy-chain disease (μ-HCD)** | Truncated monoclonal **IgM heavy chain**; neoplastic cells often also produce monoclonal light chains, usually **κ**, that fail to assemble with the truncated heavy chain (pqac-00000006, pqac-00000007) | **Approx. historical case count:** **30-40** reported; predominantly **Caucasian males**, median age **58 years**; mainly **bone marrow**, often with features resembling **CLL/SLL**; splenomegaly frequent, hepatomegaly in ~**25%**, superficial lymphadenopathy in **40%** (pqac-00000006) | Usually a lymphoid neoplasm with **CLL/SLL-like** features. Characteristic marrow morphology shows plasma cells with **prominent cytoplasmic vacuoles** admixed with small round lymphocytes. Reported associations include recurrent pulmonary infections, portal hypertension, pancytopenia, SLE, DLBCL of the breast, MDS, carpal tunnel syndrome, systemic amyloidosis (pqac-00000006, pqac-00000007) | Serum electrophoresis generally normal or shows a broad monoclonal band; **anti-μ immunofixation positive** and **anti-κ/anti-λ negative** confirms the heavy-chain component. **Bence Jones proteinuria is frequent** because excess light chains are produced but do not assemble; hypoproliferative anemia is the commonest lab abnormality (pqac-00000006, pqac-00000007) | Because of rarity, data are limited. **Watch-and-wait** for asymptomatic patients with detectable monoclonal μ chains. If underlying malignancy develops: **CHOP**, **CVP**, **single-agent fludarabine**, or **cyclophosphamide** have been used (pqac-00000005) | Reported **median overall survival ~2 years**, ranging from **<1 month to >10 years**; likely underestimated because monoclonal μ chains are often missed on electrophoresis. **Rare spontaneous remission** reported (pqac-00000005) |


*Table: This table compares the three classic heavy-chain disease subtypes using only data extracted from the Ria 2018 full text. It is useful for quickly distinguishing epidemiology, pathology, diagnostic hallmarks, treatments, and available outcome statistics in these very rare disorders.*