Lobular Carcinoma, Not Only a Classic

Update on Lobular Neoplasia

Lobular neoplasia (LN) is a histopathologic entity that encompasses both lobular carcinoma in situ (LCIS) and atypical lobular hyperplasia (ALH). Management of LN is known to be variable and institutionally dependent. The variability in approach after a diagnosis of LN at percutaneous breast biopsy derives in part from heterogeneity in the literature, resulting in a range of reported upgrade rates to malignancy after initial identification at percutaneous biopsy, and also from historical shifts in understanding of the natural history of LN. It has become increasingly recognized that not all LN is the same and that distinct variants of LN such as pleomorphic LCIS and florid LCIS have distinct natural histories and distinct likelihoods of upgrade to malignancy. In addition, it is also increasingly understood that appropriate management of LN relies on scrupulous radiologic-pathologic correlation. This review details the imaging features and histopathologic nature of ALH, classic-type LCIS, and the LCIS variants; addresses changes in the historical understanding of this entity contributing to confusion regarding its management; and discusses the importance of performing radiologic-pathologic correlation after percutaneous biopsy to help guide appropriate management steps when LN is encountered. In addition to the short-term implications of an LN diagnosis in terms of upgrade and surgical outcomes, the long-term implications of an LN diagnosis regarding risk of developing a later breast cancer are examined. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Genomic profiling of pleomorphic and florid lobular carcinoma in situ reveals highly recurrent ERBB2 and ERRB3 alterations

Pleomorphic LCIS (P-LCIS) and florid LCIS (F-LCIS) are morphologic variants distinguished from classic LCIS by marked nuclear pleomorphism and/or an expansile growth pattern with or without necrosis. Given the rarity of these LCIS variants, little data exist regarding their molecular pathogenesis, natural history, and optimal management. The purpose of this study was to genomically profile LCIS variants to gain further insight into their biology. Nineteen cases of pure LCIS variants (17 P-LCIS, 2 F-LCIS) diagnosed on core needle biopsy at our institution from 2006 to 2017 were included, five of which were upgraded to invasive cancer at excision. Macrodissected lesions were analyzed by a hybrid-capture next generation sequencing assay that surveyed exonic sequences of 447 genes for mutations and copy number variations (CNVs) and 191 regions across 60 genes for structural rearrangements. LCIS variants were all confirmed as E-cadherin negative by immunohistochemistry. Receptor profiles among the 17 P-LCIS cases included HR+/HER2- (nine cases), HR+/HER2+ (three cases), HR-/HER2+ (two cases), and HR-/HER2- (three cases). The two F-LCIS cases were HR+/HER2- and HR+/HER2+. All LCIS variants had genetic alterations consistent with a lobular phenotype including 1q gain (16 cases), 16q loss (18 cases), and CDH1 mutations (18 cases). Highly recurrent ERBB2 alterations were noted including mutations (13 cases) and amplifications (six cases). Other significant alterations included mutations in PIK3CA (six cases), RUNX1 (four cases), ERBB3 (four cases), and CBFB (three cases), as well as amplification of CCND1 (five cases). A TP53 mutation was identified in one case of HR-/HER2+ P-LCIS with signet ring cell features that lacked 1q gain and 16q loss. P-LCIS and F-LCIS contain genetic alterations characteristic of lobular neoplasia; however, these LCIS variants are distinguished from classical LCIS reported in the literature by their highly recurrent ERBB2 alterations.

A comparison of the imaging features of pleomorphic and classical invasive lobular carcinoma

PURPOSE

Pleomorphic invasive lobular carcinoma (pILC) is a distinct morphological variant of ILC with a poorer prognosis than classical ILC (cILC). The aim of this study was to ascertain whether the conventional imaging appearances of the two entities differ.

METHODS

A single-center retrospective review of conventional imaging was undertaken in 150 consecutive patients with histopathologically confirmed ILC (38 pILC; 112 cILC) between April 2010 and July 2015. Mammographic and sonographic findings were evaluated using the BI-RADS lexicon by a radiologist blinded to pathology, and the findings in the two groups were compared. The degree of discrepancy between imaging and pathological sizing in the two groups was evaluated.

RESULTS

Lesions were mammographically occult in 11% of pILC and 14% of cILC (p = 0.56). On mammography, skin or trabecular thickening and microcalcification were commoner in pILC than cILC (13% vs. 1%, p < 0.01; 25% vs. 5%, p < 0.01). Architectural distortion was more frequent in cILC than pILC (26% vs. 9%, p = 0.01). On ultrasound, pILC more frequently exhibited mixed echogenicity (28% vs. 13%; p = 0.04), skin thickening, subcutaneous or parenchymal edema (8% vs. 0%; p = 0.02), echogenic surrounding fat (33% vs. 9%; p < 0.01), and posterior acoustic enhancement (10% vs. 1%; p = 0.02) than cILC. CILC was more frequently manifested as a focal area of altered echogenicity (24% vs. 8%; p = 0.04). Mean elastography stiffness was higher for pILC (174.8 vs. 124.6 kPa; p = 0.02). Imaging-pathological size disparity was similar for both subtypes.

CONCLUSION

There are differences in the imaging features between pILC and cILC which reflect the more aggressive nature of pILC.

Pancreatic metastasis from invasive pleomorphic lobular carcinoma of the breast: a rare case report

Background

Invasive pleomorphic lobular carcinoma (PLC) is an aggressive subtype of invasive lobular carcinoma of the breast, which has its own histopathological and biological features. The metastatic patterns for PLC are distinct from those of invasive ductal carcinoma. In addition, pancreatic metastasis from PLC is extremely rare.

Case presentation

We report a rare case of a 48-year-old woman presenting with clinical gastrointestinal symptoms and pancreatic metastasis of PLC. The pancreatic tumor was composed of pleomorphic tumor cells arranged in the form of solid sheets and nests and as single files, with frequent mitotic figures, nucleolar prominence, high nuclear to cytoplasmic ratio and loss of cohesion. The malignant cells were positive for p120 (cytoplasmic) and GATA3 and negative for estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, E-cadherin, gross cystic disease fluid protein 15 and mammaglobin, which indicated a lobular carcinoma phenotype of the breast.

Conclusions

To the best of our knowledge, this is one of the few reported cases in the literature of pancreatic metastasis of invasive lobular carcinoma of the breast, of which the definitive diagnosis was obtained only after surgery. Rare metastasis sites should be considered, particularly, when a patient has a medical history of PLC.

Core Breast Biopsies Showing Lobular Carcinoma In Situ Should Be Excised and Surveillance Is Reasonable for Atypical Lobular Hyperplasia

OBJECTIVE

The purpose of this article is to determine the upgrade rate to ductal carcinoma in situ (DCIS) or invasive carcinoma at excision at the same site after percutaneous breast biopsy findings of atypical lobular hyperplasia (ALH) or lobular carcinoma in situ (LCIS) using current imaging and strict pathologic criteria.

MATERIALS AND METHODS

From January 2006 through September 2013, 32,960 breast core biopsies were performed; 1084 (3.3%) core biopsies found ALH or classic LCIS. For 447 lesions in 433 women, this was the only high-risk lesion at that site, with no ipsilateral malignancy, and results of excision were available.

RESULTS

Among the 447 lesions, 22 (4.9%) were malignant at excision, including 10 invasive carcinomas (two grade 2 and eight grade 1; all node negative) and 12 DCIS. The upgrade rate of LCIS was 9.3% (10/108; 95% CI, 5.1-16.2%) and that of ALH was 3.5% (12/339; 95% CI, 2.0-6.1%; p = 0.02). After excluding five cases with radiologic-pathologic discordance and reclassifying one core from ALH to LCIS at review, the upgrade rate for LCIS remained higher (8.4%; 9/107; 95% CI, 4.5-15.2%) than that for ALH (2.4%; 8/335; 95% CI, 1.2-4.6%; p = 0.01).

CONCLUSION

Excision is recommended for LCIS on core biopsy because of its 8.4-9.3% upgrade rate. Excluding discordant cases, patients with other high-risk lesions or concurrent malignancy, the risk of upgrade of ALH was 2.4%. Surveillance at 6, 12, and 24 months can be performed in lieu of excision because a short delay in diagnosis of the few malignancies is not expected to cause harm.

Invasive Pleomorphic Lobular Carcinoma of the Breast: Pathologic, Clinical, and Therapeutic Considerations

Pleomorphic lobular carcinoma is an uncommon form of breast cancer and a subtype of invasive lobular carcinoma. It has unique histopathologic features that translate to a more aggressive phenotype with an associated poor prognosis. Unlike classical invasive lobular carcinoma, it can lose estrogen and progesterone receptor expression and demonstrate HER-2/neu amplification. It remains to be determined, however, whether the pleomorphic histology independently predicts a worse outcome or whether other known associated negative prognostic factors such as larger tumor size, increased metastatic disease, and associated worse molecular subtypes commonly present in pleomorphic carcinoma account for the poor prognosis. Here we present an updated review of the unique pathologic and clinical features of pleomorphic lobular carcinoma needed to guide management for women with this subtype of cancer.

Clinical outcome in pleomorphic lobular carcinoma: a case-control study with comparison to classic invasive lobular carcinoma

Pleomorphic lobular carcinoma (PLC), a variant of invasive lobular carcinoma (ILC) is described as an aggressive tumor with poor prognosis. Multiple studies show lower overall survival for patients with PLC than for patients with classic ILC (cILC). We compared the clinicopathologic characteristics of PLC with those of cILC. All cases with a diagnosis of ILC, Nottingham grades 2 or 3 that were diagnosed between January 1, 1990, and December 31, 2010, were retrieved from pathology files in the institutional anatomic pathology database. The cases (N = 52) were reviewed to identify those meeting the criteria for PLC. An E-cadherin immunostain was used to confirm the lobular immunophenotype. Clinicopathologic data were assessed and analyzed. A control group (N = 103) of cILC, Nottingham grade 1, was selected, with 2 controls for each case, matched by age and year of diagnosis. PLC was associated more closely with in situ carcinoma (P = .03), and had lower progesterone receptor expression (P = .03) than cILC. Both disease-free survival and overall survival were similar between patients with PLC and matched cILC controls, and both depended on disease stage, tumor size, and lymph node status. PLC is similar to cILC in terms of patient survival and outcomes.

Underestimation rate of lobular intraepithelial neoplasia in vacuum-assisted breast biopsy

OBJECTIVES

To evaluate the underestimation rate and clinical relevance of lobular neoplasia in vacuum-assisted breast biopsy (VABB).

METHODS

A total of 161 cases of LN were retrieved from 6,435 VABB. The histological diagnosis was ALH (atypical lobular hyperplasia) in 80 patients, LCIS (lobular carcinoma in situ) in 69 patients and PLCIS (pleomorphic lobular carcinoma in situ) in 12 patients. Seventy-six patients were operated on within 2 years after VABB and 85 were clinically and radiologically monitored. The mean follow-up was 5.2 years, and the prevalence of malignancy was evaluated in the group of 85 patients.

RESULTS

The clinico-pathological characteristics significantly favouring surgery were larger lesions, occurrence of a residual lesion following VABB and histological LCIS and PLCIS subtypes. The VABB underestimation rate as compared to surgery was 7.1% for ALH, 12% for LCIS and 50% for PLCIS. Overall, 11 of the 148 patients included in this survival analysis developed an ipsilateral tumour.

CONCLUSION

Although obtained retrospectively in a relatively small series of patients, our data suggest that only patients with a diagnosis of PLCIS in VABB should be treated with surgery, whereas patients with ALH and LCIS could be monitored by clinical and radiological examinations.

KEY POINTS

• The treatment of ALH and LCIS in VABB is still debated • Some authors favour radical treatment and others a more conservative approach • Only patients with PLCIS in VABB should be treated by surgery.

When is excision necessary for atypical lobular hyperplasia and lobular carcinoma in situ?

SUMMARY This management perspective briefly covers the histology and molecular features of lobular in situ neoplasia and provides an in-depth discussion of the need for surgical excision if lobular in situ neoplasia is diagnosed on core-needle biopsy. The management of lobular in situ neoplasia found on core-needle biopsy has been an area of recent study with varying results. Emerging data suggest that low-risk patients with a limited extent of isolated classic lobular in situ neoplasia found on core-needle biopsy may not require subsequent surgical excision. However, high-risk patients, those with extensive lobular in situ neoplasia, or other high-risk lesions noted on core-needle biopsy likely benefit from surgical excision. Most authors recommend surgical excision when pleomorphic lobular carcinoma in situ is found on core-needle biopsy due to its higher association with invasive carcinoma. However, the natural history of this more recently described variant of lobular carcinoma in situ is not fully defined, and the clinical management of pleomorphic lobular carcinoma in situ on excisional biopsy is yet to be determined.

Radiologic-pathologic correlation at breast MR imaging: what is the appropriate management for high-risk lesions?

Breast magnetic resonance (MR) imaging is increasingly performed for a variety of indications, most commonly with the goal of detecting breast cancer. Percutaneous biopsy (usually under MR guidance or ultrasound if there is a correlating finding) is commonly used to evaluate suspicious imaging findings detected on MR imaging with the goal of identifying malignancy. It is important to be familiar with the characteristics and management of high-risk lesions detected or biopsied under MR guidance. This review focuses on the appearance of a variety of breast lesions detected on MR imaging that require excision with focus on pathologic correlation.

[Pleomorphic lobular intraepithelial neoplasia: clinical, histological and prognostic study of nine cases]

INTRODUCTION

Retrospective clinical, histological and prognostic study of nine cases of lobular intraepithelial neoplasia in its pleomorphic subtype (LIN-P).

PATIENTS AND METHODS

Analysis of our center database with selection of nine cases of LIN-P from 140 files of patients who underwent surgical excision with a final diagnosis of LIN (2000 to 2011). The medical files were reviewed with a re-analysis of the mammograms and the histological slides. The outcome of the patients was also analyzed according to their clinical and operative data.

RESULTS AND DISCUSSION

The average age at diagnosis was 63 years (later than common LIN [LIN-C]). All patients had mammograms classified ACR 4 and 5, mainly due to the presence of microcalcifications (seven cases) with a case of opacity associated with microcalcifications, and two other cases with only isolated opacities. The preoperative diagnosis of these lesions was difficult: five cases on nine core needle biopsies were reviewed and reclassified LIN-P after finding the presence of LIN-P on the surgical specimen. Associated invasive lesions were found in 55% of core needle biopsy and in 33% of cases of surgical resection specimen. The treatment included a wide surgical excision (five lumpectomies and four mastectomies with a patient who had two lumpectomies) with margins of more than 2mm: we noted a recurrence of LIN-P only in one case where margins were very close (1mm). The analysis of our cases confirms that LIN-P if they probably share the same origin as the LIN-C represent a particular form constituting a true precancerous condition warranting at least a wide surgical excision.

Are the imaging features of the pleomorphic variant of invasive lobular carcinoma different from classic ILC of the breast?

The aim of this study was to evaluate whether pleomorphic invasive lobular carcinoma (PILC) is different from classic invasive lobular carcinoma (CILC) in terms of radiologic and clinicopathologic features. We compared the radiologic and clinicopathologic features of 22 surgically confirmed PILCs in 21 patients from 2004 to 2009 and 47 CILCs from 47 consecutive patients. For all cases, we reviewed the imaging findings, medical records and pathological results. PILC had a higher T stage, N stage, nuclear and histologic grade compared to CILC. PILC was more commonly negative for estrogen receptors and positive for HER2 than CILC (all p < 0.05). However, there were no significant differences in age, symptoms, tumor size, extensive intraductal component, lymphovascular invasion, triple negative profile, or multiplicity between the two groups. PILC was not detected on mammography in 1 (4.5%) of 22 cases, whereas CILC was not detected on mammography in 7 (14.9%) of 47 cases and on MRI in 2 (5.0%) of 40 (p = 0.42 and p = 1.000, respectively). MRI identified more frequent multiplicity than mammography for both PILC and CILC (p < 0.001), but was similar to US (p = 0.066). Most lesions showed a spiculated mass or architectural distortion with or without calcifications on mammography and ultrasound. No differences in mass and/or non-mass lesions or kinetics on MRI were observed between the two groups. PILC shows more pathologically aggressive features, but cannot be differentiated from CILC based on imaging findings.

Low frequency of cancer occurrence in same breast quadrant diagnosed with lobular neoplasia at percutaneous needle biopsy

PURPOSE

To determine the type of mammographic abnormality leading to needle biopsy of lobular neoplasia (LN) and define the clinical evolution of low-risk LN lesions diagnosed at needle biopsy but not surgically removed.

MATERIALS AND METHODS

This study was approved by the institutional review board, and the requirement to obtain informed consent was waived. Among 16 945 needle biopsies performed between April 1998 and August 2008, LN was determined to be the most suspicious lesion in 352 samples (2.1%) (pleomorphic and necrotic forms were excluded). Among 299 pure LN lesions that were not surgically removed, follow-up was available for 276 lesions in 275 women.

RESULTS

Needle biopsy was performed because of mammographic calcifications in 215 of the 276 lesions (77.9%) and because of mammographic masses in 35 (12.7%). The mean follow-up was 5.0 years ± 2.4 (range, 0.6-12.2 years). All 275 women underwent one mammographic follow-up, 205 (74.5%) underwent a second mammographic follow-up, and 147 (53.5%) underwent a third mammographic follow-up. Cancer was diagnosed in 27 of the 275 cases (9.8%) after a mean of 3.9 years ± 2.6 (range, 1.2-10.8 years). Only three cancers (1.1%) occurred in the same breast quadrant as the one originally diagnosed with LN at needle biopsy.

CONCLUSION

Lumpectomy of pure LN lesions may not prevent malignancy in most cases. Consequently, women with pure LN of a low-risk type diagnosed at needle biopsy are strongly encouraged to undergo a yearly breast clinical examination and yearly mammographic follow-up to detect an eventual cancer in its early stages.