Sarcoidosis

Sarcoidosis
Idiopathic. Granulomatous disease (non-caseating).
Systemic disease involving the lymph nodes, lungs, liver, heart etc.
Lung is the most commonly involved organ.

Clinical features:
- 3rd or 4th decades
- More in African american
- 70% have increased serum ACE - An indicator of the granuloma burden on the body

Nuclear Medicine:
- Gallium (Ga 67 scintigraphy) avid during active phase. No uptake when in remission.
Degree of uptake corresponds to degree of severity
Confirms diagnosis of sarcoidosis
Differentiate active alveolitis from inactive fibrosis
Signs:

1. Lambda sign: Hilar and Right paratracheal nodal uptake
2. Diffuse pulmonary uptake
3. Panda sign: Lacrimal and salivary glands inflammation

- PET scan: FDG avid during active phase. SUV can be >2.5

Acute Sarcoidosis

aka Lӧfgren syndrome
Clinical features:
- Fever, malaise, arthralgia +/- parotitis / uveitis
- Erythema nodosum
- Serum ACE level often increased
- Erythema nodosum
Has bilateral hilar lymphadenopathy, but absence of lung changes

Lungs:

Garland’s triad (1-2-3 sign)
Lambda sign on Gallium scan

1. Bilateral hilar lymphadenopathy
2. Right paratracheal lymphadenopathy

CXR:

-          Reticulonodular opacities, bilateral upper lobe dominant

-          Symmetric bilateral hilar, paratracheal, aortopulmonary window lymphadenopathy

HRCT:

-          Lymphadenopathy
-     1-5mm nodules in centrilobular and subpleural distribution
-     Upper lobe and peribronchovascular distribution
-     Irregular interlobular septal thickening
-     Architectural distortion

-          Advanced: Interstitial fibrosis- Peripheral honeycombing, Bullae
-     Some cases (rare): Alveolar sarcoidosis = Peripheral consolidation + Mediastinal and Bilat.hilar lymphadenopathy

Radiographic staging:
-     Stage 0: Normal CXR

-          Stage I: disease limited to mediastinal nodes

-          Stage II: involvement of lung and lymph nodes

-          Stage III: involvement of lung only

-          Stage IV: lung fibrosis

DDx:
- When advanced, can mimic progressive massive fibrosis (PMF)

Cardiac

Result in:
- Arrhythmia
- Ventricular aneurysms
- Sudden death

Head & Neck:

Involvement of glandular tissues, muscles, nerves.
1. Optic nerve and EOM hypertrophy and enhancement - uveitis
2. Parotid glands and lacrimal glands exhibits heterogeneous bilateral symmetrical enlargement - chronic dacroadenitis, parotitis

Gallium scan: "Panda sign" where there is increased uptake of the parotid and lacrimal glands (Looks like the whole panda sitting on the person's neck / replacing the head)

Neurological system:

Neurosarcoidosis, 5% of sarcoidosis patient
Usually lungs would have been involved already.
Granulomatous infiltration of the perineural tissue
Involvement of nerves, optic chiasm, hypothalamus, infundibulum, IAM
Presenting with cranial nerve deficits

Imaging:
Exhibit contrast smooth / nodular enhancements along the involved nerves, thickened leptomeninges, pachymeninges
Also enhancement in the perivascular space, ependyma
5% have solitary extra-axial mass

Complication: Hydrocephalus

Gastrointestinal:

Spleen:
Splenomegaly
Present as splenic granulomas, +/- calcification
If present = advanced stage of Sarcoidosis.
Spontaneous splenic rupture (rare)

Lymph nodes:
Mesenteric nodes

Musculoskeletal:

Affect small bones of hands and feet
Reticulated trabecular pattern (lace-like)
Cyst-like lesions
Destruction of terminal phalanges
Diffuse sclerosis of the vertebral bodies
Osteolysis in skull