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| Web: | mayocliniclabs.com |
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| Email: | mcl@mayo.edu |
| Telephone: | 800-533-1710 |
| International: | +1 855-379-3115 |
| Values are valid only on day of printing | |
A 65-year-old woman presents with a palpable, mobile mass in the 2 o’clock position of the right breast. Ultrasound shows a circumscribed, homogenous, hypoechoic 2.3 cm mass. Needle core biopsy shows short fascicles of proliferating spindle cells with bland oval nuclei, background of stromal collagen, foci of adipocytes, and patchy perivascular lymphocytic infiltrate. Immunohistochemical studies reveal the proliferating cells are strongly desmin, ER, PR, and vimentin positive with negative staining for p63, CK5, CD34, CD68, SMA, S100, and HMB-45.
The correct answer is ...
The correct answer is: myofibroblastoma.
Myofibroblastoma
A myofibroblastoma is a benign mammary stromal tumor, which can present as a slow-growing, painless mass (1). A myofibroblastoma is composed of fibroblasts and myofibroblasts. The epithelial and myoepithelial cells are not involved (2).
While myofibroblastomas can grow as large as 15 cm in diameter, most are noted to be less than 3 cm (1). Grossly, myofibroblastomas are well-circumscribed, unencapsulated masses with rubbery cut surfaces (2). Microscopic examination reveals bland, spindled cells in short, intersecting fascicles with thick collagen bundles woven throughout (1). The mitotic activity of a myofibroblastoma is minimal (3). Mature adipose tissue may be present.
Immunohistochemical studies are positive for desmin, CD34, ER, PR, and AR. A majority (70%-80%) of cases will show a loss of RB1 expression due to a 13q14 deletion identified by fluorescent in situ hybridization (FISH) studies (1).
Myofibroblastomas have a good prognosis. After surgical resection, myofibroblastomas do not tend to recur. It is thought that the etiology of myofibromas is hormone-based, with most cases presenting in elderly males and post-menopausal females (2).
The clinical presentation of this case combined with the histomorphology and staining pattern is compatible with this diagnosis.
Invasive lobular carcinoma
Invasive lobular carcinoma generally presents with a palpable breast mass and radiologic findings of a spiculated mass. Grossly, invasive lobular carcinoma appears as an ill-defined lesion. The classic morphology shows proliferative, discohesive cells that invade through the breast stroma in a single-file linear pattern (4). The lesional cells show round-to-ovoid nuclei, a thin rim of cytoplasm, and occasional cytoplasmic inclusions (4, 5). Invasive lobular carcinoma is noted for the loss of E-cadherin expression, most commonly due to the CDH1 gene mutations, causing the lesional cells to become discohesive and display the characteristic invasive pattern (6).
Immunohistochemistry for invasive lobular carcinoma will be positive for ER, PR (about 70%), and negative for E-cadherin (1).
Metaplastic spindle cell carcinoma
Metaplastic carcinoma is actually a group of invasive breast carcinomas with neoplastic epithelial differentiation toward squamous or other mesenchymal components (1). This includes a spindle cell carcinoma displaying atypical, elongated spindle cells with moderate to high cytologic atypia and associated inflammation (7). Metaplastic spindle cell carcinoma tends to present in advanced stages in association with DCIS, and carries a poor prognosis (1, 7).
Immunohistochemistry studies show positivity for p63, high molecular weight keratins, and AE1/AE3. The proliferating cells will be negative for ER, PR, HER2 (triple negative), desmin, and CD34 (7).
Nodular fasciitis
Nodular fasciitis is a benign proliferation of fibroblast/myofibroblast cells. Nodular fasciitis tends to be a rapidly growing tumor, over the span of several weeks, ultimately becoming self-limiting over the course of a few months (8). Grossly, nodular fasciitis appears as a well-circumscribed encapsulated mass. The morphology of nodular fasciitis shows bland-appearing myoblasts or fibroblasts with a mixture of myxoid or collagen stroma, varied cellularity, brisk mitotic activity, and increased vasculature with extravasated red blood cells (9).
Immunophenotype of nodular fasciitis will be SMA positive with focal desmin expression while being negative for cytokeratin, CD34, S100, and beta-catenin.(1)
Rachel Horton, D.O.
Resident, Anatomic and Clinical Pathology
Mayo Clinic
@RachelHortonDO
Charles Sturgis, M.D.
Senior Associate Consultant, Anatomic Pathology
Mayo Clinic
Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science
A 62-year-old grain farmer is admitted to the hospital with worsening respiratory symptoms after completing treatment for presumed bacterial pneumonia. The patient has Type 2 diabetes and previously underwent heart transplantation. Due to a peripheral cavitary lung lesion on imaging, patient underwent bronchoalveolar lavage (BAL) with lesion biopsy. Image 1 shows the KOH-Calcofluor White stain of the tissue. Image 2 is from a cellophane tape preparation after two days of culture growth stained with lactophenol aniline blue.
The correct answer is ...
The correct answer is: Hyphae suggestive of Mucorales and the cellophane tape preparation resembles Rhizopus species.
Mucormycosis, previously called zygomycosis, is a serious but rare invasive fungal infection. A diagnosis of infection with one of the Mucorales is often a medical emergency due to the rapid spread of infection, angioinvasive nature of the mold, and high mortality rate.
Mucorales infections are often seen in individuals with uncontrolled Type 2 diabetes, malignancy, or those on long-term immunosuppression. Mucorales are found ubiquitously in the environment and infection occurs most often by inhalation of the spores or inoculation after a skin injury. The most common types of infections are rhinocerebral, pulmonary, cutaneous, and disseminated. Mucormycosis can be diagnosed from a direct microscopic examination of the clinical specimen stained with KOH-Calcofluor White, as seen in Image 1. The image shows characteristic ribbon-like hyphae fragments that are twisted, folded, and collapsed. The hyphae are large, wide, and pauciseptate. The hyphae are fragile because they lack septations and can often be damaged in processing in the laboratory, yielding low recovery in microbiologic culture. Similar to its rapid spread in the human body, Mucorales also grows quickly in the laboratory as a white, wooly mold filling the entire plate and pushing the lid upwards, giving rise to their nickname as the “lid-lifters”.
There are multiple genera of Mucorales that infect humans, but the two most common agents causing infection are Rhizopus and Mucor. These two genera can be distinguished by their microscopic morphologies after growth in culture. Image 2 shows Rhizopus species, with nodal rhizoids, occurring directly underneath the sporangiophore or stalk. The round, sac-like object full of spores and responsible for asexual reproduction is the sporangium, which is attached to the sporangiophore. Mucor is an incorrect answer because rhizoids are not present in this species.
Other useful methods for identification of the Mucorales in the microbiology laboratory include MALDI-TOF mass spectrometry and Sanger sequencing. When the laboratory has high suspicion for or confirmation of Mucorales in a specimen, this a critical result and the care team should be immediately notified. Due to the invasive nature of the organism, this will often require additional surgical debridement as the primary patient management strategy. Amphotericin B is the primary antifungal of choice, and either posaconazole or isavuconazole is used in combination and for stepdown therapy.
Allison Eberly, Ph.D.
Fellow, Clinical Microbiology
Mayo Clinic
@ali_eberly
Nancy Wengenack, Ph.D.
Consultant, Clinical Microbiology
Mayo Clinic
Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science
A 68-year-old immunocompetent man developed a headache after returning from a vacation in Australia and New Zealand. Initially thought to be a sinus infection, patient was prescribed systemic and nasal antibiotics as well as nasal steroids. Two months later he returns with worsening symptoms, including profound fatigue, imbalance with left leg weakness, and blurry vision in his right eye. MRI of the brain and spine show multiple masses, and a biopsy of a mass shows necrotizing granulomatous inflammation. H&E and GMS stains identified the organism in Images 1 and 2, respectively, and CSF cultures were positive for two gray-black colonies after one month.
The correct answer is ...
The correct answer is: Cladophialophora bantiana.
Cladophialophora bantiana, a dematiaceous fungus, is the most common causative agent of cerebral phaeohyphomycosis (1). C. bantiana is found worldwide, although its exact ecological niche is still unknown. Infections can be caused by minor traumatic implantation, but pulmonary and disseminated disease is caused by the inhalation of conidia (1, 3). C. bantiana, like other dematiaceous fungi, is pigmented due to the presence of melanin in its cell walls. C. bantiana grows well on standard fungal media and produces dark colonies with a velvet-like texture and discreetly grooved topography (Image 3). Cellophane tape preparations of the colonies show long chains of smooth, lemon-shaped conidia (Image 4). Although species-level identification can be made using these classic morphologic features, identification of C. bantiana using MALDI-TOF mass spectrometry or sequencing from early fungal growth is generally faster and safe for lab staff because identification often can occur prior to production of the mature, infectious conidia. Culture plates should be taped securely shut and the organism inactivated by autoclaving.
In a review of 101 cases of phaeohyphomycosis, C. bantiana was the most common agent of CNS infections and uniquely, a majority (73%) of the patients were immunocompetent, but it can also infect immunocompromised patients (2). A majority of the patients presented with brain abscesses. Clinical symptoms amongst the patients were varied, and typical symptoms included headache, neurologic deficits, and seizures, although rarely all three were present. Almost all of the patients (86%) were diagnosed based on histopathological findings. Overall mortality rate amongst the patients was 70%. There is no standard therapy for the treatment of C. bantiana CNS infections, but better outcomes were observed in patients who underwent complete excision of the abscess (2). Combination therapy of AmBisome, flucytosine and itraconazole has also shown improved treatment efficacy. This patient was treated with a combination of AmBisome, flucytosine and voriconazole. Therapeutic drug monitoring of voriconazole and follow-up genetic testing determined that the patient was a rapid metabolizer and omeprazole was added to increase serum concentrations of voriconazole.
In tissues, dematiaceous fungi usually have a characteristic appearance of irregularly swollen hyphae with yeast like structures in contrast to Aspergillus species which typically show septate, acutely branching, straight walled hyphae (3). It can be difficult to distinguish Aspergillus and dematiaceous fungi based on GMS stains, but pigmentation visible on H&E stains or melanin-specific Masson-Fontana stains can also help distinguish dematiaceous fungi from other moulds.
Rhinocladiella mackenziei is also a pigmented fungus that can cause human cerebral phaeohyphomycosis but is endemic solely to the Middle East (1). Phialophora species are dematiaceous fungi that most commonly cause chromoblastomycosis (1). Traumatic implantation of these organisms cause cutaneous or subcutaneous infections with warty, tumor-like, or cauliflower-like lesions. Unlike C. bantiana, in tissues Phialophora species seen as sclerotic bodies which are brownish, muriform, septated cells also coined as “copper penny bodies.”
Anisha Misra, Ph.D.
Resident, Clinical Microbiology
Mayo Clinic
@MisraAnisha
Nancy Wengenack, Ph.D.
Consultant, Clinical Microbiology
Mayo Clinic
Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science
Bobbi Pritt, M.D.
Division Chair, Clinical Microbiology
Mayo Clinic
Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science
@ParasiteGal
Thirteen-day-old girl with hypotonia, born to parents who achieved the pregnancy using in-vitro fertilization (IVF). No other significant family history was available. The provider wanted to evaluate for a diagnosis of Prader-Willi syndrome (PWS) or Angelman syndrome (AS) and, if positive, desired to clarify the disease mechanism.
The correct answer is ...
The correct answer is: maternal heterodisomy for chromosome 15, <1% risk.
Prader-Willi syndrome (PWS) is characterized by severe hypotonia and feeding difficulties in early infancy, followed in later infancy/early childhood by excessive eating and gradual development of morbid obesity (unless eating is externally controlled). Motor milestones and language development are delayed. All individuals have some degree of cognitive impairment. A distinctive behavioral phenotype (with temper tantrums, stubbornness, manipulative behavior, and obsessive-compulsive characteristics) is common. Hypogonadism is present in both males and females and manifests as genital hypoplasia, incomplete pubertal development, and, in most, infertility. Short stature is common (if not treated with growth hormone); characteristic facial features, strabismus, and scoliosis are often present.
Consensus clinical diagnostic criteria are accurate, but the mainstay of diagnosis is DNA methylation testing to detect abnormal imprinting patterns within the Prader-Willi critical region (PWCR) on chromosome 15; this testing determines whether the region is maternally inherited only (i.e., the paternally contributed region is absent) and has a sensitivity of at least 99%. DNA methylation-specific testing is important to confirm the diagnosis of PWS in all individuals, but especially in those who have atypical findings or are too young to manifest sufficient features to make the diagnosis on clinical grounds.
The MS-MLPA result for this patient shows absence of a deletion (unmethylated reaction); however, the digested reaction shows two copies of a methylated allele at maternally imprinted sites compared to a normal control. This result is consistent with a diagnosis of Prader-Willi syndrome.
To clarify disease mechanism, microsatellite markers are analyzed and compared between the parents and proband to evaluate for uniparental disomy. The results shows that the proband has inherited both copies of chromosome 15 from the mother (UPD15), and since non-identical alleles are present, this is consistent with heterodisomy.
Below is the recurrence risks for different mechanisms for Prader-Willi syndrome and Angelman syndrome.
Vishnu Vardhan Serla, M.D.
Fellow, Molecular Genetic Pathology
Mayo Clinic
@ vishnuserla
Nicole Lynn Hoppman, Ph.D.
Consultant, Laboratory Genetics and Genomics
Mayo Clinic
Associate Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science
A 47-year-old man was referred to the genomics laboratory for alpha thalassemia testing because of microcytosis without anemia. Dosage analysis (PCR and Multiplex Ligation Probe Analysis) was used to detect deletion and duplication-type mutations and the Hb Constant Spring and alphaT Saudi point mutations within the alpha globin gene cluster. This method uses multiple probes that hybridize throughout the alpha-gene locus on chromosome 16 from the HS-40 regulatory region through the 3' hypervariable region.
The correct answer is ...
The correct answer is: ααα(anti-4.2)/-3.7α; Additional studies are required to determine if the abnormalities are in cis or trans in order to explain the patient’s phenotype.
Alaa Koleilat, Ph.D.
Resident, Laboratory Genetics and Genomics
Mayo Clinic
Linda Hasadsri, M.D., Ph.D.
Consultant, Laboratory Genetics and Genomics
Mayo Clinic
Assistant Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science
A 23-year-old patient who has a son with Fragile X syndrome (FXS) is pregnant with another son. She requested genetic testing as soon as possible to determine if the current pregnancy is also affected with FXS. A chorionic villus sample was taken at 12.5 weeks gestation for FXS testing by repeat-primed PCR (see A for results). Follow-up methylation studies were performed, including methylation-sensitive digestion followed by repeat-primed PCR (see B for results).
The correct answer is ...
The correct answer is: report full mutation, but request follow-up methylation studies by amniocentesis at 15 weeks gestation.
Report full mutation, but request follow-up methylation studies by amniocentesis at 15 weeks gestation — Correct. At 12.5 weeks gestation, methylation and gene imprinting is not fully established. Thus, follow-up testing by amniocentesis at 15 weeks gestation is required to determine if the full mutation (>200 CGG repeats) is truly methylated (resulting in FMR1 silencing and FXS) or unmethylated (at risk for FXTAS)1. Note: It’s not uncommon to see extra peaks in patients with full mutations due to the instability of the allele; this could represent low-level size mosaicism. These could also just be artifact or signal bleed-through due to the nature and sensitivity of this assay.
Laura Thompson, Ph.D.
Resident, Laboratory Genetics and Genomics
Mayo Clinic
Linda Hasadsri, M.D., Ph.D.
Consultant, Laboratory Genetics and Genomics
Mayo Clinic
Assistant Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science
