| Abstract|| |
Although carcinoid tumor is a relatively common neoplasm in surgical pathology, fine needle aspiration cytology (FNAC) as a method of primary diagnosis has only been reported a few times. We report the case of a 55-year-old male patient who presented with colicky pain in the abdomen and a vague mass in the right lumbar region. Ultrasonographic study showed an enlarged mesenteric lymph node. Ultrasonography-guided FNAC revealed cellular smears with neuroendocrine cellular arrangement and morphology. The cytomorphologic characteristics of carcinoid tumors are distinctive enough for diagnosis. A diagnosis of metastatic carcinoid was given. 5-hydroxyindolacetic acid in 24-hour urine turned out to be high. Histopathology and immunohistochemistry studies also confirmed the diagnosis. Thus, FNAC can be a useful and safe tool in the diagnosis of carcinoid tumors.
Keywords: Carcinoid, fine needle aspiration cytology of lymph node, metastatic tumors in lymph node, neuroendocrine tumors
|How to cite this article:|
Naniwadekar MR, Desai S R, Dombale V D, Kulkarni S R. Diagnosis of metastatic carcinoid in mesenteric lymph node by fine needle aspiration cytology. Indian J Pathol Microbiol 2008;51:424-6
|How to cite this URL:|
Naniwadekar MR, Desai S R, Dombale V D, Kulkarni S R. Diagnosis of metastatic carcinoid in mesenteric lymph node by fine needle aspiration cytology. Indian J Pathol Microbiol [serial online] 2008 [cited 2022 Jan 19];51:424-6. Available from: https://www.ijpmonline.org/text.asp?2008/51/3/424/42550
| Introduction|| |
Carcinoid or neuroendocrine tumors are located throughout the gastrointestinal tract. Midgut carcinoids (involving jejunum and ileum) may be multiple and most of them have mesenteric lymph node metastasis.  Fine needle aspiration cytology (FNAC) can play an important role in diagnosing neuroendocrine tumors. Attention to the presence of loose cell clusters in a background of singly dispersed cells, feathery pattern created by tumor cells, clinging to capillaries, delicate granular cytoplasm, inconspicuous nucleoli and speckled chromatin patterns are useful in identifying neuroendocrine differentiation in cytologic specimens. 
| Case History|| |
A 55-year-old male patient was admitted with chief complaints of pain in the abdomen for 5-6 months, which was colicky and intermittent in nature and loose motions with watery stools for 10-12 days. He gave a history of anorexia, insomnia and weight loss in the last 3-4 months.
On per-abdominal examination, a vague mass was palpable in the right lumbar region and right iliac fossa. Routine hematological and biochemical studies were within normal limits, except for hemoglobin, which was 10.4 gm%. Ultrasonographic (USG) study showed a segmental wall thickening of distal ileum with a focal high-grade narrowing, suggestive of stricture with adjacent mass of mesenteric lymph nodes. Ultrasonographic diagnosis was small intestinal tuberculosis with mesenteric lymphadenopathy. USG-guided FNAC of the mesenteric lymph node was done.
Cytologic findings - Highly cellular smears showed small, monomorphic, oval-to-cuboidal cells arranged in small sheets, clusters and adherent to capillaries. The cells showed round-to-oval regular nuclei with granular nuclear chromatin and scanty amount of cytoplasm. Many small capillary structures were seen. The background showed red blood cells. A diagnosis of metastatic carcinoid (neuroendocrine tumor) was suggested [Figure 1].
5-hydroxyindolacetic acid level in 24-hour urine was asked for, which was 13.6 mg in 24-hour urine sample and was definitely high (the normal value being 2-6 mg/24 hours).
Contrast-enhanced computed tomography (CECT) scan of the abdomen, after using oral contrast, was done. A diagnosis of terminal ileal malignancy, with a differential diagnosis of carcinoid tumor and malignant lymphoma was suggested.
Right hemicolectomy including terminal ileum and mesenteric lymph node mass with ileotransverse end-to-end anastomosis was performed.
Gross findings - A specimen of terminal ileum, caecum with appendix and ascending colon was received. Constrictions at three levels were seen in the ileum, which on opening showed elevated lesions, the largest measuring 3 × 2 cm in dimension, with partial obliteration of lumen of the intestine. Cut section through the lesion showed yellowish white appearance, involving the entire thickness of the intestine, with the thickness measuring 1.2 cm.The mesentery adjoining the constriction showed a lymph node mass measuring 4.5 × 3 × 2 cm, which on cut section showed a homogeneous yellowish appearance [Figure 2].
Microscopic findings - Sections from all the three lesions in the intestine showed a tumor, predominantly in the submucosa, consisting of cells arranged in nests, trabeculae and ribbon-like fashion. The cells were uniform, round with monotonous round nuclei, showing finely stippled chromatin and a moderate amount of cytoplasm. An occasional mitotic figure was seen. The largest lesion showed tumor infiltration into the muscularis propria, serosa and the adjoining adipose tissue. The mesenteric lymph node was completely replaced by the tumor. A diagnosis of carcinoid tumor (well-differentiated neuroendocrine carcinoma) with metastatic carcinoid to mesenteric lymph node was offered.
The tumor cells expressed synaptophysin and chromogranin on immunohistochemistry.
The patient is on regular follow-up and is symptom-free and is leading a good-quality life for the last 2 years.
| Discussion|| |
Carcinoid or neuroendocrine tumors are located throughout the entire gastrointestinal tract. With the possible exception of appendiceal carcinoids, all others are considered neoplasms with malignant potential.  FNAC can play an important role in diagnosing neuroendocrine tumors. On FNAC, in 'classic carcinoid tumor', the findings are distinctive enough to permit diagnosis, with or without ancillary tests such as electron microscopy or immunocytochemistry. , The 'neuroendocrine' round-to-oval nuclei, with stippled nuclear chromatin and inconspicuous nucleoli and plexiform background of small blood vessels with adherence of cells to vascular core are distinctive. In metastases, a plexiform vascular pattern may not be seen well.  In the present case, the smears of FNAC of mesenteric lymph node showed all the findings suggestive of neuroendocrine tumor, including plexiform vascular pattern. So the diagnosis of 'metastatic carcinoid' was offered.
Collins et al stated that the cytomorphologic characteristics of carcinoid tumors are distinctive and appropriate ancillary studies can assist in confirming the diagnosis. Necrosis or prominent nucleoli are not seen in classic carcinoid.  If features such as necrosis, increased mitotic activity, or pleomorphism are noted, a diagnosis of atypical carcinoid should be favored. 
Nicholson et al  tried to correlate cytologic findings in neuroendocrine carcinomas with histologic findings and tried to identify features most suggestive of neuroendocrine differentiation. According to them, presence of loose cell aggregates, feathery patterns created by tumor cells clinging to capillaries, delicate granular cytoplasm, inconspicuous nucleoli and speckled chromatin pattern are useful in identifying neuroendocrine differentiation in cytologic specimens. At the same time, if acinus-like formations and columnar cell shapes are seen, they may be mistaken for adenocarcinomas. Large cell neuroendocrine carcinomas may be confused with non-neuroendocrine carcinomas, because of abundant cytoplasm and prominent nucleoli.  The differential diagnosis also includes epithelioid gastrointestinal stromal tumor. However, on immunocytochemistry, the neuroendocrine tumor cells are positive for chromogranin and negative for CD34. 
In a study of FNAC of neuroendocrine tumors below the diaphragm, by Leiman et al , diagnostic specificity and sensitivity were 100%. 
An increased 5-hydroxyindolacetic acid in 24-hour urinary excretion indicates neuroendocrine origin of the tumor or the possibility of a carcinoid syndrome.  The level of 13.6 mg in 24-hour urine sample in the present case was definitely high (the normal value being 2-6 mg/24 hours) and thus confirmed the functional nature of the tumor. Although frequent watery stools, one of the feature of carcinoid syndrome, has been assumed to be due to 5-hydroxy tryptamine, there is little relation between the serum levels of this marker and the occurrence of the syndrome. 
The patient underwent right hemicolectomy including terminal ileum and mesenteric lymph node mass with ileotransverse end-to-end anastomosis. Multicentric tumors were seen in ileum, the largest measuring 3 × 2 cm, involving the entire thickness of the wall, with a large mesenteric lymph node. In the small intestine affected by carcinoid tumor, 35% of patients have multicentric (two or more than two) tumors.  Those larger than 2 cm are almost always malignant and they present with regional lymph node metastasis.  It has been observed that the patients who underwent resection for the primary tumor had a longer survival than those with no resection and patients who underwent successful excision of mesenteric lymph node metastasis had a significantly longer survival than those with remaining lymph node metastasis and also led to a significant reduction in tumor-related symptoms.  Though surgery prolongs survival, it is rarely curative.  Other cytoreductive strategies and radioreceptor therapy may offer new therapeutic options; but their definite value is yet to be defined.
A significant pre-operative weight loss, which was seen in this case, is identified as a major negative prognostic factor for survival. But in the present case, the patient is symptom-free and leading a good-quality life for the last 2 years.
This case is presented to stress the crucial role played by FNAC in the diagnosis of carcinoid tumor and to report the distinctive findings on cytology. We conclude that the cytomorphologic features of classic carcinoid are distinctive enough to diagnose without the ancillary studies. Ancillary studies can assist in supplementing the diagnosis.
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Manjiri Ramchandra Naniwadekar
Naniwadekar Hospital, Market Yard, Shaniwar Peth, Karad - 415 110, Dist.- Satara (Maharashtra)
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]