SP Web 2-16-04
Case 1 A thirteen year-old male with a paratesticular mass.
Diagnoses:
A. Embryonal Rhabdomyosarcoma
B. Alveolar Rhabdomyosarcoma
C. Mixed Embryonal and Alveolar Rhabdomyosarcoma
D. Mixed Embryonal and Alveolar Rhabdomyosarcoma with Diffuse Anaplasia
Answer: D, Mixed Embryonal and Alveolar Rhabdomyosarcoma with Diffuse Anaplasia
Histologic Description:
The majority of this lesion has the classic spindle-cell morphology of an embryonal rhabdomyosarcoma. Strap cells and spindle-shaped cells with abundant cytoplasmic cross striations are readily evident. In addition, there is a small round blue cell component, which is discohesive and focally has multinucleated tumor giant cells with “wreath-like” nuclei. These features are classic for alveolar rhabdomyosarcoma. In addition, there are multiple nuclei throughout the lesion which are markedly enlarged (threefold compared to adjacent nuclei) with abnormal, bizarre mitoses. These cytologic features would meet the criteria for anaplasia in Wilms’ tumor, and therefore this lesion is classified as a diffusely anaplastic rhabdomyosarcoma.
The classic spindle cell paratesticular rhabdomyosarcoma has a fascicular or storiform pattern that suggests either leiomyosarcoma or a fibrohistiocytic lesion. It lacks the high cellularity, diffuse nuclear anaplasia, or round cell component seen in the current lesion. This current tumor has both alveolar morphology and diffuse anaplasia, both of which are associated with a diminished prognosis.
Case 2 Four year-old male with a mediastinal mass demonstrated incidentally on a CT scan performed for coughing.
Diagnoses:
A. Ganglioneuroblastoma
B. Neuroblastoma, stroma poor, differentiating
C. Ganglioneuroma
D. Neuroblastoma, stroma-rich differentiating
Answer: B. Neuroblastoma, stroma poor, differentiating
Histologic Description:
This tumor appears to arise from clusters of native ganglion cells and Schwann cells, likely from a cervical sympathetic ganglion located paravertebrally. The tumor is composed of neuroblasts and abundant ganglion cells, set in abundant neuropill. There is not a significant Schwann cell stromal component as the Schwann cells are limited to fibrovascular septa within the tumor. Therefore, this lesion is stroma-poor (less than 50% Schwann cells) but differentiating (> 5% ganglion cells in a background of neuroblasts). It has virtually no mitotic activity, and therefore at this age range would still qualify as Shamada-favorable.
Differential Diagnosis:
Ganglioneuroblastoma should have greater than 50% ganglion cells and greater than 50% Schwannian stroma. Ganglioneuroma should have abundant Schwannian stroma and pure ganglion cells, without admixed neuroblasts.
Case 3 A 43 year-old male with an intradural mass arising from the cauda equina.
Diagnoses:
A. Carcinoid tumor involving a ganglion
B. Neuroblastoma
C. Schwannoma
D. Cauda Equina Paraganglioma
Answer: D, Cauda Equina Paraganglioma
Histologic Description:
This is an unusual tumor that has a variety of components. Much of the tumor consists of ribbons of bland epithelioid cells with a ribbon-like architecture reminiscent of carcinoid tumor. There are admixed ganglion cells and abundant Schwann cells. In other foci, the epithelioid cells have a highly nested pattern typical of paraganglioma.
Differential Diagnosis:
Involvement of native ganglia by a carcinoid tumor is excluded by the history. The diagnosis of Schwannoma does not account for the epithelioid cells and presence of ganglion cells.
The current lesion is an example of a paraganglioma of the central nervous system, which are almost exclusively located in the cauda equina. Most of these lesions are entirely intradural and attached to the filum terminale. Nearly half of cauda aquina paragangliomas contain mature ganglion cells. They also have architectural features reminiscent of carcinoid tumor, including angiomatous, ribbonlike, and pseudo-rosette patterns. In a sense, cauda aquina paragangliomas are analogous to the “gangliocytic paragangliomas” found in the duodenum. These lesions are usually cured by complete excision. Occasional tumors have recurred or metastasized, usually following sub-total resection. Cauda aquina paragangliomas are also distinctive in that they are known to label (focally) for cytokeratins, unlike other paragangliomas.
References:
J Clin Pathol 1998; 51:477-478
Cancer 1986; 58:1720-1735
Case 4 A fifty-seven year-old female with a recurrent anal polyp.
Diagnoses:
A. Inflammatory Cloacogenic Polyp
B. Active Chronic Inflammatory Disease consistent with Ulcerative Colitis
C. Ulcerated Adenomatous Polyp, Rule Out Carcinoma
D. Inflammatory Polyp
Answer: A, Inflammatory Cloacogenic Polyp
Histologic Description:
This lesion occurs at a squamo-glandular junction and therefore it is centered on the anus histologically. The lesion features ulcerated granulation tissue, fibromuscular obliteration of the lamina propria, reactive epithelial changes simulating adenoma, and marked crypt distortion, mimicking idiopathic chronic inflammatory bowel disease. The crypts often have a diamond-shaped morphology. Inflammatory cloacogenic polyps are easily mistaken for neoplastic processes, because the marked reactive epithelial changes may simulate a neoplasm. The marked architectural disorder and acute inflammatory changes may suggest ulcerative colitis, though the clinical picture should help make this distinction. An inflammatory polyp is essentially a polypoid mass of granulation tissue, lacking the epithelium present in this case.
Inflammatory cloacogenic polyp is one of a number of lesions which may arise through mucosal prolapse. Other such lesions include solitary rectal ulcer syndrome, with colitis cystica profundica if the mucosa herniates deep into the submucosa, polypoid prolapsing mucosal folds adjacent to diverticula, ostomy site-associated prolapse, gastritis cystica profunda after Billroth II resections, and prolapse within adenomatous polyps. The key features of these lesions are: inflammatory ulcerations and reactive epithelial changes, crypt distortion, and fibromuscular obliteration of the lamina propria. The crypts often have a diamond shape. Inflammatory cloacogenic polyp typically occurs on the anterior wall of the anal-rectal junction, and often recurs. Its location may relate to the loose tethering of the rectal mucosa at its junction with the anal squamous mucosa.
Case 5 A forty-eight year-old female with a breast mass.
Diagnoses:
A. In situ and Infiltrating Lobular Carcinoma
B. In situ and Infiltrating Apocrine Ductal Carcinoma
C. Infiltrating Apocrine Carcinoma in a background of Fibrocystic Changes
D. Atypical Apocrine Adenosis
Answer: B, In situ and Infiltrating Apocrine Ductal Carcinoma
Histologic Description:
The lesion is composed entirely of apocrine cells; that is, cells with abundant granular pink cytoplasm, and nuclei with generally vesicular chromatin and prominent nucleoli. There is an infiltrating component characterized by desmoplasia and irregularly placed tumor cell nests. The presence of in situ carcinoma is confirmed by the presence of similar cells within ducts showing coarse chromatin, irregular nuclear membranes, irregularly-shaped prominent nucleoli and necrosis. Focal cribriform architecture is also identified.
Differential Diagnosis:
Lobular carcinoma may occasionally have apocrine features, but should not show the marked pleomorphism and gland formation seen in the current case. The irregular shape of the nests and presence of desmoplasia is diagnostic of invasion. The marked nuclear chromatin irregularities and presence of necrosis allow one to diagnose this lesion as apocrine DCIS, as opposed to an atypical apocrine proliferation. This distinction can otherwise be difficult, since benign apocrine lesions are typically monotonous and have uniform cytology with prominent nucleoli.
While many invasive breast cancers show apocrine features focally (particularly when evaluated by immunohistochemistry for GCDFP), pure apocrine carcinomas such as the current lesion are rare, comprising less than 4% of cases. These tumors are typically negative for estrogen and progesterone receptor (as the current case was) but strongly positive for the androgen receptor. There is no evidence that this histologic pattern is in and of itself associated with a better or worse prognosis once stage and grade are accounted for.
Reference: Advances in Anatomic Pathology 2004; 11: 1-9.
Case 6 A seventy-six year-old female with a sub-areolar breast mass.
Diagnoses:
A. Sclerosing Papilloma
B. Adenomyoepithelioma
C. In situ Papillary Carcinoma
D. Ductal Adenoma
Answer: C, In situ Papillary Carcinoma
Histologic Description:
This is an unusual lesion in that the tumor cells, while monotonous, have a dimorphic appearance. Some of the nuclei have abundant clear cytoplasm, and appear to undermine other cells with less cytoplasm and darker nuclei. The proliferation is supported by fibrovascular cores, making it a papillary lesion. Between fibrovascular cores, there is rigid cribriform growth with both morphologies, indicating that this is in fact an in situ carcinoma and not a florid hyperplasia. Dimorphic cytology has been reported within in situ papillary carcinomas of the breast.
Differential Diagnosis:
Papillomas should feature both epithelial cells and myoepithelial cells, and lack the cytologic monotony seen in the current lesion. Adenomyoepithelioma is essentially a variant of papilloma with prominent myoepithelial cells; myoepithelial cells are not present in the current lesion. A ductal adenoma is essentially a sclerotic papilloma with superimposed sclerosing adenosis, which was not present in the current lesion.