UNKNOWNS

Question 1

18 yo with breast mass

Answer 1

INVASIVE SECRETORY CARCINOMA

Infiltrative ductal process assoc w/ irregular border and mild stromal desmoplasia

Cells form tubules and cribriform structures and assoc w/ intracellular and extracellular eosinophilic secretions

Minimal ER/PR, unlike most low nuclear grade breast cancers

FISH - ETV6-NTRK3 rearrangement

Question 2

This is a 32 year old male with a paraspinal mass.

Answer 2

SCHWANNOMA

Highly cellular spindle cell neoplasm with occasional mitotic figures.

Permeates bone suggests aggressive process

Hyalanized vessels and lower cellularity typical of schwannoma

IHC: S100+

(malignant peripheral nerve sheath tumors are typically NOT diffusely S100+ like schwannoma and demonstrate greater atypia and mitotic activity)

Question 3

This is an 87 year old female with a 1 cm breast mass.

Answer 3

METAPLASTIC CARCINOMA

Fairly well delineated fibroblastic nodule with extensive hyalinization (layered, plaque like)

Subtle infiltration at the edge of the lesion and abrupt variations in cellularity which raise suspicious fro metaplstic carcinoma.

Spindle cells are diffuse pos for high molecular weight keratin (34BE12)

DDX:

1. Fibroadenoma - would not label for HMW-keratin, CD34+
2. Sclerosed papillomas - hylanized rounded appearance but HMW-keratin negative
3. Duct ectasia - markedly dilated ducts assoc with squamous metaplasia and periductal chronic inflammation and histiocytes

Question 4

50 year-old male with a colon mass

Answer 4

INFLAMMATORY FIBROID POLYP

Large polypoid lesion seen on this histiologic section was grossly attached to the cecal wall by a thin stalk.

Surface is lined by bland appearing colonic mucosal glands with regions of acute inflammation and ulceration. The center contains irregular but benign appearing colonic glands; abudnant goblet cells are present and cells have low N:C ratio.

The stroma = bland spindled cells with blunt-ended euchromatic nuclei, occasional punctate nucleoli and no atypia

Numerous eosinophils within stromal space and prominent thick-walled blood vells and vague suggestion of “onion skinning” around blood vessels

Question 5

30 year-old female with a colon mass

Answer 5

ENDOMETRIOSIS

Question 6

50 year-old male with a spine mass

Answer 6

SCHWANNOMA

Benign peripheral nerve sheath tumors comprised of neoplastic Schwann cells

Spindle cells with wavy nuclei, tapering ends

Alternating hypocellular w/ myxoid matrix (Antoni B) and hypercellular (Antoni A). Prominent bands of nuclear palisading (Verocay bodies).

Scattered blood vessels within lesion but no notable hyalinzation.

Mitotic activity is rare and necrosis is absent

diffusely S100+

Question 7

A 45 year old male presented with a 3 cm. testicular mass.

Answer 7

BENIGN LEYDIG CELL TUMOR

Fairly well-circumscribed but unencapsulated mass with intersecting bands of eosinophilic collagen

Minimal entrapped seminiferous tubules seen at periphery of nodule

Surrounding interstitium shows normal Leydig cells

Tumor sheets without tubular formation (vs Sertoli). Neoplastic cells are polygonal in shape with fairly abundant lightly eosinophilic cytoplasm, which areas at the edge of the tumor show vacuolization. Round nuclei with small consicuous nucleoli.

No mitosis or necrosis

IHC: SF-1+, Inhibin +

Question 8

A 65 year old man presents with hematuria and a papillary tumor in the bladder.

Answer 8

Papillary tumor of uncertain malignant potential (PUNLMP)

• Discrete, delicate, non-fused papillae
• Urothelium overtly thick, even at low magnification.
• Cytology is normal or at most slightly enlarged nculei with some cells having nuclear grooves. Umbrella cells are inconspicuous.
• Mitotic figures are virtually absent or at most rarely seen towards the basement membrane
• 30% risk of recurrence over 15 years, rarely recur as high grade/invasive
• No concurrent invasion

Vs benign urothelial papilloma –> thickness is overtly thicker than normal urothelium

Vs low-grade papillary urothelial carcinoma –> complete lack of cytological atypia without larger hyperchromatic nuclei

Question 9

A 15 year old male was noted to have a paratesticular mass.

Answer 9

Embryonal rhabdomyosarcoma with anaplasia

• Tumor consists of cellular spindle cell and small blue cell tumor
• Focally eosinophilic spindling of the cytoplasm. Some cells are anaplastic with large pleomorphic nuclei and markedly atypical mitotic figures

In paratesticular regions - overtly malignant pleomorphic spindle cell tumor in

• adult is almost always a de-differentiated liposarcoma
• child/young adult is rhabdomyosarcoma

Question 10

This is a 71 year old male with an axillary mass

Answer 10

METASTATIC MELANOMA

• Lymph node contains sheets of epithelioid cells with vesicular chromatin, prominent nucleoli and eccentric pink cytoplasm (“rhabdoid” phenotype)
• Abudnant mitotic activity & central necrosis
• At the edge are less pleomorphic cells forming nests rather than sheets –> mark for melanA HMB45 and SOX10

Question 11

This is a 6 year old male with 9 cm renal mass

Answer 11

NEPHROBLASTOMA

• Unecapsulated neoplasm which is epithelial predominant
• Most of the noeplasm consists of tubules lined by primitive columnar cells with mitotic activity, diagnostic of epithelial Wilms tumor
• Areas at the edge where it is more differenentiated, more cuboidal, less mitotically active and associated with sclerotic stroma and psammomatous microcalfications –> resemble metanephric adenoma (not uncommon for Wilms tumors to have areas within them that resemble this)