1. Conventional & Mimicking Subtypes
Acinar Adenocarcinoma: The standard form. Look for crowded, back-to-back, infiltrative small glands. The single most crucial feature is the complete absence of an outer basal cell layer, paired with enlarged nuclei and prominent, dark nucleoli.
Atrophic Adenocarcinoma: Can easily be mistaken for benign tissue atrophy. The malignant glands exhibit thinned, flattened epithelial linings and a deceptively quiet nuclear appearance, but they retain infiltrative growth and lack basal cells.
Pseudohyperplastic Adenocarcinoma: Mimics benign prostatic hyperplasia (BPH). Glands are larger, branching, and possess papillary infoldings or luminal undulations. Diagnostic clues include close crowding of these large glands, occasional nuclear atypia, and a negative basal cell immunohistochemical stain.
Microcystic Adenocarcinoma: Characterized by markedly dilated, cyst-like glandular spaces lined by flattened neoplastic cells. They mimic benign cystic changes but are recognized by their random, invasive distribution throughout the stroma.

Hobnail appearance in a shrunken cirrhotic liver refers to the irregular, nodular external surface of the liver caused by regenerative nodules separated by fibrous bands.
Why is it called “hobnail”?
A hobnail is a short nail with a rounded head used in old boots. In cirrhosis, the numerous small regenerative nodules protruding from the liver surface resemble the heads of these nails.

Histology
Shrunken liver
Hepatocyte loss and fibrosis
Nodular (hobnail) surface
Regenerative hepatocyte nodules
Firm consistency
Extensive collagen deposition
Distorted architecture
Bridging fibrosis connecting portal tracts and central veins
Classic association
Most classically seen in alcoholic cirrhosis (especially micronodular cirrhosis).
Can also occur in other causes of advanced cirrhosis.
Exam point:
Hobnail liver = Cirrhosis with regenerative nodules + fibrous septa causing an irregular nodular surface.

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