Congenital lymphatic hypoplasia in unilateral lower limb with abnormal technetium-99m sulphur colloid uptake in both breasts.

We present a patient with Meige like lymphedema (left lower limb hypoplasia) with asymptomatic minimal accumulation of Technetium-99m sulfur colloid in bilateral breasts. We attribute the possible pathology to accumulation of interstitial fluid in hypoplastic left lower limb leading to dilatation of the remaining outflow tracts and valvular incompetence. This may be causing reversal of flow from subcutaneous tissues into the dermal plexus involving the breast. Other possibilities include formation of spontaneous lymphovenous shunt or lymphatic intercommunication at lower trunk level as a result of increased pressure leading to minimal lymph accumulation in breasts. Later a mammogram was performed which was found to be normal. MR also confirmed no cisterna chyli abnormalities or aberrant lymphatic channels in lower thorax region that may be the explanation for the abnormal sulphur colloid uptake in both breasts.

INTRODUCTION

Lymphedema develops from obstruction, dilation of valves, valvular insufficiency, and subsequent reversal of lymphatic flow. Small collateral vessels interconnecting the superficial and deep systems may be formed in these conditions. Lymphedema gets compounded by reduced lymphatic transport capacity resulting in the stagnation of high-molecular-weight proteins in the interstitium. We report the first case of a young lady with suspected congenital lower limb lymphedema showing abnormal subtle accumulation of 99mTc sulphur colloid in bilateral breasts evident only in delayed images of a lower limb lymphoscintigram.

CASE REPORT

A 28-year-old female patient presented with swelling and pain of the left foot, especially in the mornings since 2 years. Patient has a 3-year-old child and gives no history of taking oral contraceptive pills. She had no family history of lymphedema. On local examination, there was diffuse pitting edema of the left foot and ankle extending up to mid-calf region. Skin over dorsum of left foot was thickened. Left inguinal lymph nodes were enlarged, discrete, and nontender on palpation. No distal neurovascular deficits seen. Xray of left foot and Doppler study were noncontributory. Patient has no known congenital anomalies. Bilateral upper limbs were normal and had no features to suggest any associated lymphedema.

Patient was referred to our department for lower limb lymphoscintigraphy to rule out any lymphatic dysfunction. 37 MBq of filtered technetium-99m (99mTc) Sulfur colloid in two equally divided doses were injected intradermally over first and second interdigital web spaces of feet. Initial images of lower limbs show good progression of colloid particles through right lower limb lymphatic channels with normal visualization of right inguinal lymph nodes. No progression of colloid particles noted through left lower limb lymphatic channels. A few left inguinal nodes were faintly seen in delayed images. Findings suggest unilateral left lower limb lymphatic hypoplasia [Figure 1]. In addition, abnormal colloid accumulation was noted in bilateral breasts (bold arrow) and lower trunk region (dotted arrow) appreciable only in 2 h delayed images. An abnormal lymphatic communication at lower trunk level was suspected. Further to lower limb lymphoscintigraphy, patient underwent clinical examination of breasts, and bilateral mammogram, which was found to be normal. Magnetic resonance (MR) [Figure 2] of thorax showed cisterna chyli as a single straight thin tube (thin arrow) between the aorta and the right hemidiaphragmatic crus thus ruling out any cisterna chyli malformation No aberrant lymphatics were also noted to explain the bialteral breast sulphur colloid uptake in this patient.

Figure 1

Technetium-99m sulfur colloid lower limb lymphoscintigraphy: Normal lymphatic flow seen through right lower limb. No progression of colloid particles noted through left lower limb lymphatic channels in initial image. A few faint left inguinal nodes are visualized in delayed images. Findings suggest left lower limb lymphatic hypoplasia. Delayed image at 2 h also showed abnormal minimal accumulation of tracer in bilateral breasts (bold arrow) and lower trunk region (dotted arrow) suggesting abnormal lymphatic intercommunication at lower trunk level or reversal of lymphatic flow into breasts through Garota's paramammary route.

Figure 2

Coronal T2-weighted magnetic resonance image acquired with a half-Fourier acquisition single-shot turbo-spin-echo sequence shows a normal (small) cisterna chyli as a single straight thin tube (thin arrow) between the aorta and the right hemidiaphragmatic crus. The thoracic duct is not seen. Thick arrow depicts one of the lumbar/intestinal afferent trunks. No aberrant lymphatics noted

We therefore hypothetically attribute the possible pathology to accumulation of interstitial fluid in hypoplastic left lower limb leading to dilatation of the remaining outflow tracts and valvular incompetence. This may be causing reversal of flow from subcutaneous tissues over the anterior abdominal wall into the dermal plexus involving the breasts. Other possible explanations include breast lymphatics may be draining through the Gerota's paramammary route which is getting intercommunicated by microlymphatics at lower trunk level or there may be spontaneous lymphovenous shunt formation. As patient was asymptomatic and investigations revealed no structural breast abnormalities, patient was advised close follow-up to look for any overt clinical changes in breasts.

DISCUSSION

Primary (congenital) lymphedema can occur in one out of every 6000 people. Based on the timing of presentation, congenital lymphedema is called as Milroy's disease (at birth), lymphedema praecox or Meige's disease (at puberty), and lymphedema tarda (during adulthood). Meige's disease usually affects lower extremity and is unassociated with other congenital anomalies.

Primary lymphedema[12] affects an estimated 1.15 in 100,000 people younger than 20 years of age. Primary lymphedema is pathophysiologically classified into (a) large vessel abnormalities such as congenital aplasia of the thoracic duct or cysterna chyli, (b) congenital lymphatic valvular incompetence or congenital aplasia and (c) lymph node fibrosis. Patients who present later in life may have acquired lymphatic obstructive disease, the cause of which is still obscure. Clinically, it is classified as Milroy's disease when present from birth, painless, without tendency to ulcerate, and may have cholestasis or intestinal lymphangiectasia associated with it. Meige's disease, (hereditary lymphedema praecox), is lymphedema with onset in the first or second decade, often presenting with inflammation, and may have a number of associated related anomalies. Both types follow an autosomal dominant pattern.[3] Patients with Meige lymphedema usually have at least one other affected family members. When the condition occurs in only one person in a family, the condition is described as Meige-like lymphedema. Individuals with Meige lymphedema usually develop swelling during puberty. The swelling typically occurs in the lower legs and feet. Females are affected three times more than males. Based on the time and mode of presentation our case was considered to be a case of Meige like lymphedema.

Here we discuss briefly the normal mechanism of lymphatic flow[4] and the possible mechanism of abnormal accumulation of sulphur colloid in breasts. Lymphatic drainage occurs through a superficial and deep system. Superficial dermal lymphatics are unvalved, drain into interconnected subdermal channels and further into the deeper, epifascial system of valved trunks lined with smooth muscle cells. Valves provide unidirectional flow towards regional lymph nodes and eventually into the venous circulation in the neck. A deeper-valved (subfascial) system of lymphatics is responsible for the lymph drainage from the fascia, muscles, joints, and bone. Epifascial and subfascial systems normally function independently, although connections exist in the popliteal, inguinal, antecubital, and axillary levels where lymph nodes form interconnected chains. These connections probably do not function under normal conditions. However, in lymphedema, some reversed flow through perforators from the epifascial to the subfascial system may occur along with small collateral vessels formation

Sappy's plexus forms the main route of lymphatic drainage of breast which drains into the axillary or internal mammary lymph nodes. It has been explained that breast lymphatic vessels may also rarely drain through abdominal wall vessels (Gerota's paramammary route)[5] which may be another possible explanation of reversal of flow or intercommunication of 99mTc sulphur colloid from the lower thoracic lymphatics.

Aberrant lymphatics identified by lymphoscintigraphy have been rarely reported. Jain and Jaimini[6] have reported a case of congenital hypoplasia of lower limb lymphatics with visualization of bilateral axillary lymph nodes in lower limb and scrotal lymphoscintigraphy without visualization of liver. They concluded that patient had an aberrant lymphatic pathway, possibly secondary to malfunctioning/nonfunctioning thoracic duct. We found no report or literature evidence of aberrant lymphatics leading to slow accumulation of colloids in otherwise normal breasts to explain our case. Poor labeling of 99mTc sulfur colloid was also ruled out as a discrete lymphatic tract was visualized in the right lower limb and there was no free pertechnetate in the preparation as thyroid gland, stomach or urinary tract was not seen in initial or delayed images. We are attributing the abnormal smearing of tracer in lower trunk region to abnormal micro communication in lymphatic channels in the setting of normal MR imaging as no other possible explanation or literature report exists for aberration in lymphatic supply leading to sulfur colloid accumulation in bilateral breasts.

CONCLUSION

This is the first case illustrating unilateral lower limb lymphatic hypoplasia with asymptomatic abnormal 99mTc sulfur colloid accumulation in bilateral breasts. No possible cause of lymphatic dysfunction could be identified on MR. A possible explanation of breast draining through Gerota's paramammary route or microscopic lymphatic intercommunication in lower thorax was entertained in a background of unilateral lower limb lymphedema. This abnormal micro communication may be the cause of the slow trickle of sulfur colloid in bilateral breasts.