Erythema induratum is a panniculitis on the calves. It occurs mainly in women, but it is very rare now. Historically, when it has occurred, it has often been concomitant with cutaneous tuberculosis, and it was formerly thought to be always a reaction to the TB bacteria. It is now considered a panniculitis that is not associated with just a single defined pathogen. The medical eponym Bazin disease was historically synonymous, but it applies only to the tuberculous form and is dated. Pathophysiology
Predisposing factors include abnormal amount of subcutaneous fat, thick ankles and abnormally poor arterial supply. Abnormal arterial supply causes low-grade ischemia of ankle region. The ankle skin becomes sensitive to temperature changes. When weather is cold, ankle is cold, blue and often tender. In hot weather, ankle becomes hot, edematous, swollen and painful. Chilblains may be present. On palpation, small superficial and painful nodules are felt. They break down to form small and multiple ulcers. Fresh crops of nodules appear in periphery of ulcer and ultimately break down. In nodular stage, pain is present; while it subsides in ulcerative stage. Diagnosis
Mainly clinical. Eponym
The name Bazin disease honors Pierre-Antoine-Ernest Bazin. Additional images
References
External links
 Media related to Erythema induratum at Wikimedia Commons
PatientPlus
Consequently, porphyrin deposits form in the bloodstream and cause neuropathic pain, leading to the acute neurological crises experienced by some patients. Additionally. SA can function to inhibit renal tubular function, the synthesis of heme, and the immune system.The accumulation of unprocessed tyrosine itself in the blood stream as a consequence of deficient catabolism can also lead to disruption of hormonal signaling and neurotransmission. Tyrosine is a precursor molecule required for synthesis of several neurotransmitters and hormones, mainly Dopamine, norepinephrine, and thryoxine. Excessive synthesis of these molecules due to elevated tyrosine levels can impair physical growth, motor function, and speech development. Diagnosis
Beyond the identification of physical clinical symptoms outlined above, the definitive criterion for diagnostic assessment of Tyrosinemia Type I is elevated succinylacetone (SA) in blood and urine. Elevated SA levels are not associated with any other known medical condition, so there is minimal risk of misdiagnosis. Quantitation of tyrosine levels is also used as a diagnostic but is less reliable due to high false positive and false negative rates. Newborns are not generally screened for HT1 due to rarity of the condition and lack of apparent symptoms at time of birth. However, prompt assessment upon the manifestation of physical symptoms such as fever, vomiting, increased tendency to bleed, diarrhea along with bloody feces, and jaundice is critical for improving long term prognosis. Management
The primary treatment for type 1 tyrosinemia is nitisinone and restriction of tyrosine in the diet.