A 70-year-old female patient was admitted with complaints of lower abdominal pain of 5 months duration. Pain was initially intermittent but steadily worsened to require management with narcotics. The patient reported constipation but denied rectal bleeding. At the time of presentation, she had urinary retention that led to the placement of an indwelling Foley catheter which revealed hematuria in the bag. She reported anorexia, nausea, abdominal bloating, and worsening of bilateral leg edema, but did not have any vomiting, hematemesis, chest pain, melena, jaundice, fever, chills, night sweats, or weight loss. Her CT scan showed a large heterogeneous but predominantly fatty pelvic mass compressing the bowel and bladder (Figure 1). Two needle core biopsies were done which revealed only benign adipose tissue. Patient was sent for upper and lower gastrointestinal endoscopies and MRI. She further complained of persistent lower abdominal and pelvic pain, and difficulty urinating. An MRI showed a 13 cm x 10 cm x 10 cm pelvic mass that appeared well encapsulated and nested between the rectosigmoid and sacrum. There was no suspicious lymphadenopathy (Figure 2). The patient was admitted for the resection of the mass with possible colostomy. She had no history of heart disease, rheumatic fever, neurological disorder, diabetes, ulcers, asthma, tuberculosis, or kidney, liver, or thyroid disease, and had no suspicious lesions on the skin. The patient underwent bilateral ureteral stent placement followed by resection of a large 18 cm sacrococcygeal tumor with en-bloc low anterior rectosigmoid resection and Hartmann's stump.
On gross examination, the tumor was an unencapsulated, tan-yellow solid mass, measuring 13 cm x 13 cm x 7 cm. The cut surface was tan-yellow, with minute foci of hemorrhage. The tumor was approximately 0.3 cm away from the adjacent colon and did not involve the same.
Histopathologically, the tumor consisted predominantly of mature adipose tissue with no atypia. Few thin and moderately thick collagen bands were noted. Foci of hemorrhage and minute areas of extramedullary hematopoiesis were identified.
Fresh tumor tissue was analyzed for chromosomal abnormalities. Routine karyotyping was done. An abnormal female karyotype was observed after examination of 20 metaphase cells. There was a clonal abnormality: all metaphases had trisomy of chromosome 5. No other abnormality was found. Fluorescence in situ hybridization (FISH) analysis of fresh tissue was done, FISH analysis summary is shown in Table 1. LSI DDIT3 and LSI FOXO1 dual color break-apart DNA probes (Vysis Inc.) were used to detect the rearrangements associated with the DDIT3 (CHOP) gene in the 12q13 region and FOXO1 (FKHR) gene in the 13q14 region, respectively. Two hundred interphase cells were examined for each probe. Within the limitations of the procedure, the hybridization produced a normal pattern for both probes, consistent with no translocations, deletions, or rearrangements of the DDIT3 (CHOP)/12q13 or FOXO1 (FKHR)/13q14 genes.
Fluorescence in situ hybridization analysis of formalin-fixed paraffin-embedded tissue was performed using the Vysis MDM2 DNA probe (Abbott Molecular Inc.), which contains two probes. The LSI MDM2 DNA probe labeled spectrum Orange, specific for the MDM2 gene locus on 12q15; while the CEP 12 DNA control probe labeled spectrum Green which is specific for DNA sequence at the centromeric region of chromosome 12p11.1-q11.2. At least 50 non-overlapping cells were scored. The results of hybridization produced an MDM2:CEP12 ratio of 1.0 (Table 2). This was consistent with no amplification of the MDM2 gene, ruling out the possibility of a well-differentiated (WD) liposarcoma. Further immunostaining with HMB-45 and MART-1 was also negative. Based on these findings a final diagnosis of adrenal myelolipoma was rendered.
Upon recent follow-up (status post-resection 3.5 years), the patient was asymptomatic with no tumor recurrence.