Spindle cell ductal carcinoma in situ. An unusual variant of ductal intra-epithelial neoplasia that simulates ductal hyperplasia or a myoepithelial proliferation

Pitfalls in breast pathology

Accurate pathological diagnosis is the cornerstone of optimal clinical management for patients with breast disease. As non-operative diagnosis has now become the standard of care, histopathologists encounter the daily challenge of making definitive diagnoses on limited breast core needle biopsy (CNB) material. CNB samples are carefully evaluated using microscopic examination of haematoxylin and eosin (H&E)-stained slides and supportive immunohistochemistry (IHC), providing the necessary information to inform the next steps in the patient care pathway. Some entities may be difficult to distinguish on small tissue samples, and if there is uncertainty a diagnostic excision biopsy should be recommended. This review discusses (1) benign breast lesions that may mimic malignancy, (2) malignant conditions that may be misinterpreted as benign, (3) malignant conditions that may be incorrectly diagnosed as primary breast carcinoma, and (4) some IHC pitfalls. The aim of the review is to raise awareness of potential pitfalls in the interpretation of breast lesions that may lead to underdiagnosis, overdiagnosis, or incorrect classification of malignancy with potential adverse outcomes for individual patients.

Use of immunohistochemical analysis of CK5/6, CK14, and CK34betaE12 in the differential diagnosis of solid papillary carcinoma in situ from intraductal papilloma with usual ductal hyperplasia of the breast

Objectives:

The aim of this study was to use immunohistochemistry to differentiate solid papillary carcinoma in situ from intraductal papilloma with usual ductal hyperplasia (IPUDH). Three types of high-molecular-weight cytokeratins (CKs) – CK5/6, CK14, and CK34betaE12 – were targeted.

Methods:

We studied 17 patients with solid papillary carcinoma in situ and 18 patients with IPUDH diagnosed by at least two pathologists. Immunohistochemical analyses used antibodies to CK5/6, CK14, and CK34betaE12 to make the differential diagnosis of solid papillary carcinoma in situ versus IPUDH. Immunohistochemical staining was scored as 0–5 using Allred score.

Results:

Immunohistochemistry with CK5/6 and CK14 antibodies produced scores of 0–3 in all patients with solid papillary carcinoma in situ and 2–5 in all patients with IPUDH. Immunohistochemical staining with CK34betaE12 antibody produced scores of 1–3 in all patients with solid papillary carcinoma and 3–5 in all patients with IPUDH. In tissues from patients with IPUDH, significantly more cells were stained with CK34betaE12 than CK5/6 (p < 0.05) or CK14 (p < 0.05).

Conclusion:

The immunoreactivity of CK5/6, CK14, and CK34betaE12 antibodies was useful to differentiate solid papillary carcinoma in situ from IPUDH. CK34betaE12 is especially useful for distinguishing solid papillary carcinoma from IPUDH.

Fine needle aspiration of spindle cell ductal carcinoma in situ of the breast: A case report and the use of ancillary tests for the differential diagnosis of metaplastic carcinoma

Spindle cell ductal carcinoma in situ (DCIS) is a recently recognized subtype of DCIS, which is associated with a very rare and unique morphology. Although the histologic features have been relatively well described in a few reports, the cytologic features have not. Even though the distinction of this lesion from usual DCIS is not crucial clinically, it should be noted that this lesion might simulate the features of metaplastic carcinoma on fine needle aspiration cytology. Here, we report a case of spindle cell DCIS in a 45-year-old female, with the detailed cytologic features, both on conventional and liquid-based preparations, along with some useful immunohistochemical staining markers for the differential diagnosis.

Invasive papillary breast carcinoma, solid variant with neuroendocrine differentiation

Invasive papillary carcinoma, solid variant is a rarely observed breast tumor. It is encountered in patients of advanced ages and has a good prognosis. After the physical examination, mammography, and ultrasonography examinations, modified radical mastectomy were applied to the 72-year-old patient, who came to our hospital complaining of a mass in the left breast. During the macroscopic analysis, a well-limited, necrotic, and bleeding tumor with a diameter of 7 cm was found in the left breast, covering almost the whole area. The case was diagnosed as invasive papillary carcinoma, solid variant with neuroendocrine differentiation, which has been reported in the literature as a result of the histopathological and immunohistochemical analysis.

Less Common Variants and Mimics of DCIS

The purpose of this review is to discuss the less common variants and mimics of ductal carcinoma in situ (DCIS). DCIS lesions are heterogeneous in clinical presentation and behavior, morphology, biomarker profile, and identified genetic aberrations. DCIS is most easily recognized when presenting with classical features. The diagnosis is more challenging when a lesion displays less common cytologic features and has architectural patterns that overlap with other benign or malignant entities.

The role of immunohistochemistry in the differential diagnosis of papillary lesions of the breast

Papillary lesions of the breast represent a heterogeneous group with differing biological behaviour. Correct diagnosis is crucial but may be difficult, as many benign and malignant papillary lesions have similar appearances. Immunohistochemistry plays a useful role in their differentiation. Myoepithelial markers can help in differentiating papilloma from papillary carcinoma, as the former usually shows a continuous layer of myoepithelial cells. In intracystic papillary carcinoma, there is controversy as to the presence of a complete myoepithelial cell layer around these lesions. p63 is the marker of choice as the staining is nuclear, cross-reactivity is minimal, and sensitivity is high. Papilloma may frequently be complicated by superimposed different types of epithelial hyperplasia, which range from usual to atypical or even ductal carcinoma in situ, and they many be morphologically similar. Basal cytokeratins (CKs) are useful to differentiate these entities; as usual hyperplasia is positive for basal CKs with a mosaic staining pattern. CK5/6 is probably the best marker. Neuroendocrine markers (chromogranin A and synaptophysin) may be positive in papillary carcinoma, particularly in the solid type, and there may be some overlap with the ductal carcinoma in situ with spindle cells or endocrine ductal carcinoma in situ. A panel of CK5/6, p63 and neuroendocrine markers can be useful in the diagnostic investigation of problematic papillary lesions of the breast. As the experience with these markers remains rather limited, it is too early to recommend basing treatment choices on these marker studies alone. Complete removal of lesion is probably still the treatment of choice.

Ductal carcinoma in situ with spindle cells: a potential diagnostic pitfall in the evaluation of breast lesions

AIMS

To evaluate the morphological features of 11 cases of breast ductal carcinoma in situ (DCIS) with spindle cells and to propose an approach to distinguish it from benign mimics. The association with neuroendocrine differentiation was also investigated.

METHODS

Cases of breast DCIS with a spindle cell component diagnosed in the Department of Pathology, Singapore General Hospital, between June 1996 and January 2003, were included in the study. The histological characteristics were documented, and immunohistochemistry for neuroendocrine markers, hormone receptors, cerbB2, smooth muscle actin (SMA) and high-molecular-weight (HMW) cytokeratins, was carried out. Electron microscopy was carried out on reprocessed paraffin-embedded material in three cases.

RESULTS

Of 11 women diagnosed with DCIS with spindle cells, four presented with nipple discharge, six with a breast lump, while one was discovered to have a screen detected density. The tumour size ranged from 3 to 41 mm. The proportion of spindle cells varied from 10% to 80% of the in-situ tumour cell population. Nuclear grade was low in seven cases and intermediate in four. Necrosis was observed in two cases. Architectural pattern was papillary in six cases, and mixed in the rest. Microinvasion was present in two cases, with possible microinvasion in another two. Immunohistochemistry for neuroendocrine markers synaptophysin and chromogranin showed positive reactivity for at least one marker in all but three cases; one of these latter cases demonstrated ultrastructural neurosecretory granules. Oestrogen and progesterone receptors were expressed in 10 and nine cases, respectively, while cerbB2 was positive in only one case. HMW cytokeratin immunoprofile revealed a general lack of immunostaining within the abnormal cell population; likewise, no positivity for SMA of the cellular proliferation was detected.

CONCLUSIONS

Almost all DCIS lesions with spindle cells disclose neuroendocrine differentiation. Although the distinction from benign florid usual hyperplasia may pose a diagnostic histological problem, the presence of diffuse neuroendocrine expression, in conjunction with the pattern of HMW keratin profile on immunohistochemistry, supports an in-situ neoplastic process. The absence of SMA immunostaining, in conjunction with negative reactivity for cytokeratins 5/6 and 14, makes the possibility of a myoepithelial proliferation unlikely.