Antibodies and other pathognomonic findings

Question 1

Gull wing pattern of erosions on x-ray with no periarticular osteoporosis

Answer 1

Erosive inflammatory OA

Question 2

Anti-histone

Answer 2

Drug induced lupus

Question 3

Onion peel appearance in the diaphysis of the femur

Answer 3

Ewing’s sarcoma

Question 4

Lytic lesion with sclerotic margins in the upper tibial metaphysis

Answer 4

Brodie’s abscess (subacute OM)

Question 5

Sun ray appearance of bone

Answer 5

Osteosarcoma

Question 6

Soap bubble appearance with no or minimal sclerosis

Answer 6

Osteoclastoma

Question 7

Anti-Ro

Answer 7

Sjogren’s (70%) - also anti-La, RhF, ANA
Neonatal lupus - rash generally fades after 6 months
Neonatal congenital heart block

Question 8

Anti-Jo1

Answer 8

Polymyositis, dermatomyositis - present in around 50% - correlated with poorer outcomes due to higher risk of pulmonary fibrosis

Other antibodies in polymyositis:
Mi-1, Mi-2, Ki and Ku

Question 9

Anti-U1 ribonucleoprotein (RNP)

Answer 9

Mixed connective tissue disease
- present in >90%

Question 10

Anti-smooth muscle antibody (SMA)

Answer 10

70% autoimmune hepatitis
40% PBC (often with anti-mitochondrial antibody)
Also present in PSC

Question 11

Periosteal tufting of the terminal phalanges

Answer 11

Hyperparathyroidism

Question 12

Looser zones
a) Which disease?
b) Classic biochemical profile of this

Answer 12

a) Osteomalacia - partial fractures without displacement

b) Low Ca, Low Phos, Low vit D
High Alk Phos
High PTH

Question 13

SLE

Answer 13

ANA in 95%
Anti-dsNDA in 50%
RhF in 40%
Anti-Sm in 25%

Question 14

Anti-La

Answer 14

Sjogren’s (70%)
SLE (15%)

Neonatal heart block (as for anti-Ro)

Question 15

Periosteal reaction

Answer 15

Osteomyelitis
- from about day 7 of infection

Question 16

Antiphospholipid antibodies

Answer 16

Lupus anticoagulant
Anti-cardiolipin
Anti- beta 2 glycoprotein

Raised in APLS, SLE and Behcet’s

Question 17

Complement
a) low C3 and C4
b) low C3 with normal C4
c) Normal C3, normal C4 but overall low complement (CH 50 test)

Answer 17

a) SLE: depletion of classical (C4) and alternative* (C3) pathways

b) Infection: depletion only of the alternative pathway

c) Risk of recurrent Neisseria gonococcal and meningitidis infection: Final common pathway impaired (with normal classical and alternative pathways)

*BBC Radio 4 is classical
*BBC 3 is alternative and infective